flotation cell 11

can flotation tanks ease chronic pain?

As a means of providing long-term relief from chronic pain, flotation tanks simply don't hold water, new research reveals. Nearly 100 people plagued by longstanding pain underwent "flotation restricted environmental stimulation therapy" (REST), and the results were disappointing, at least over the long term, German researchers found. The treatment involves floating inside a soundproof, lightless tank filled with salt water that's heated to skin temperature. The goal is to promote relaxation, alleviate stress, boost sleep quality and hopefullyprovide some measure of immediate and long-lasting pain relief. But after three weeks of REST treatment, chronic-pain relief remained elusive, the team found. "Flotation-REST, or simply floating, is the practice of lying belly-up in a tank filled with warm water so salty you float," explained study co-author Jorge Manuel. REST, he added, "was developed in the '70s but has recently grown in popularity." Yet despite anecdotal pain relief claims, its effectiveness has not been reliably tested, said Manuel, a doctoral candidate in somatosensory and autonomic therapy research at the Institute for Neuroradiology at Hannover Medical School in Hanover, Germany. REST "has never been compared to an indistinguishable placebo control," he said. To test REST's true potential, the study team focused on 99 adults with ongoing pain between 2018 and 2020. All patients had been struggling with pain for at least six months. The researchers noted that, by definition, chronic pain endures for a minimum of three months, and an estimated 20% of adults will experience such pain at some point in their lives. One-third of the patients were randomly assigned to undergo flotation tank therapy. Another third was assigned to a placebo tank environmentthe same floating tank but with diminished water buoyancy and far less sound and light control. The remaining third, the control group, were told to continue the pain control treatment they were taking at the study's launch. The flotation tank groups underwent five sessions, lasting 60 to 90 minutes each, over nearly three weeks. Pain relief was assessed one week after the last session, as well as three and six months out. In the end, both the REST group and the placebo tank group reported significant short-term drops in pain intensity and anxiety, and a reduction in the areas of their body affected by pain. But REST appeared to provide no appreciable leg up when it came to long-term chronic pain relief. "We found no long-term effects of floating on chronic pain, but strong short-term improvements," said Manuel. "These improvements were similar in the placebo group, suggesting that they might not be caused by sensory deprivation or effortless floating as previously thought. "One explanation for our findings could be that our participants showed high expectations toward the treatment. High expectations can lead to the production of pain-relieving substances, like opioids, by the body," he added. Still, Manuel noted that some of the patients "experienced much stronger improvements than others, suggesting that floating might be better suited for certain people." And, given the finding of short-term relief, he suggested that "it might be useful to combine [REST] floating, a passive intervention, with more active interventions like psychotherapy to obtain sustained long-term benefits." But Manuel cautioned that more extensive trials are needed to establish whether that type of combined intervention will work. For now, spine surgeon Dr. Daniel Park said the broad takeaway from the research is that "we do not have a great solution for people who have chronic pain. "Many people suffer from this, and seek answers and treatment for their pain," said Park, an associate professor in the orthopedics department at Oakland University's William Beaumont School of Medicine in Rochester, Mich. He was not part of the study. "But we as physicians many times cannot find the main cause of their pain," Park stressed. Surgery can sometimes help, but in many cases people with chronic pain do not get better, he acknowledged. The search is on for less invasive means of alleviating suffering, he added. Park did say "there may be a small group of these patients that could benefit from this type of [REST] treatment." However, because there are many causes of chronic pain, the challenge is to figure out the specific driver of a patient's pain problem and then determine whether REST could be a solution for that particular situation, he said. The findings were reported recently in JAMA Network Open. Explore further Which exercise regimen works best to ease lower back pain? More information: The American Academy of Family Physicians has more on chronic pain. Journal information: JAMA Network Open

Nearly 100 people plagued by longstanding pain underwent "flotation restricted environmental stimulation therapy" (REST), and the results were disappointing, at least over the long term, German researchers found.

Yet despite anecdotal pain relief claims, its effectiveness has not been reliably tested, said Manuel, a doctoral candidate in somatosensory and autonomic therapy research at the Institute for Neuroradiology at Hannover Medical School in Hanover, Germany. REST "has never been compared to an indistinguishable placebo control," he said.

To test REST's true potential, the study team focused on 99 adults with ongoing pain between 2018 and 2020. All patients had been struggling with pain for at least six months. The researchers noted that, by definition, chronic pain endures for a minimum of three months, and an estimated 20% of adults will experience such pain at some point in their lives.

One-third of the patients were randomly assigned to undergo flotation tank therapy. Another third was assigned to a placebo tank environmentthe same floating tank but with diminished water buoyancy and far less sound and light control. The remaining third, the control group, were told to continue the pain control treatment they were taking at the study's launch.

The flotation tank groups underwent five sessions, lasting 60 to 90 minutes each, over nearly three weeks. Pain relief was assessed one week after the last session, as well as three and six months out.

In the end, both the REST group and the placebo tank group reported significant short-term drops in pain intensity and anxiety, and a reduction in the areas of their body affected by pain. But REST appeared to provide no appreciable leg up when it came to long-term chronic pain relief.

"We found no long-term effects of floating on chronic pain, but strong short-term improvements," said Manuel. "These improvements were similar in the placebo group, suggesting that they might not be caused by sensory deprivation or effortless floating as previously thought.

"One explanation for our findings could be that our participants showed high expectations toward the treatment. High expectations can lead to the production of pain-relieving substances, like opioids, by the body," he added.

And, given the finding of short-term relief, he suggested that "it might be useful to combine [REST] floating, a passive intervention, with more active interventions like psychotherapy to obtain sustained long-term benefits."

"Many people suffer from this, and seek answers and treatment for their pain," said Park, an associate professor in the orthopedics department at Oakland University's William Beaumont School of Medicine in Rochester, Mich. He was not part of the study.

"But we as physicians many times cannot find the main cause of their pain," Park stressed. Surgery can sometimes help, but in many cases people with chronic pain do not get better, he acknowledged. The search is on for less invasive means of alleviating suffering, he added.

Park did say "there may be a small group of these patients that could benefit from this type of [REST] treatment." However, because there are many causes of chronic pain, the challenge is to figure out the specific driver of a patient's pain problem and then determine whether REST could be a solution for that particular situation, he said.

The findings were reported recently in JAMA Network Open. Explore further Which exercise regimen works best to ease lower back pain? More information: The American Academy of Family Physicians has more on chronic pain. Journal information: JAMA Network Open

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diagnosis of internal parasites | today's veterinary practice

The diagnosis of internal parasites in companion animals continues to evolve. Efficient methods that allow clinicians to diagnose infections more quickly and implement treatment earlier have helped pets live longer, healthier lives. Because some internal parasites spread zoonotic disease, such advances also help protect owners.

Although most parasites are associated with a particular system of the body, due to life cycle differences, evidence of their presence may be seen in a variety of places (Table 1). For this reason, more than 1 method of testing may be needed to confirm parasitic presence. In addition, attention to detail with regard to health history, aseptic collection, and processing of relevant samples as well as clinical experience in the laboratory help determine diagnostic answers.

The gastrointestinal (GI) tract plays host to a variety of helminths and protozoan parasites. Because these parasites may mature and reproduce in different areas of the GI system, there is no single best method for ova, larvae, or adult identification.

Likewise, the method and choice of flotation solution that may be used to identify parasitic ova, oocysts, or larvae will differ based on specific gravity (SG) of the organism compared to that of the chosen flotation solution. If protozoan infection of the GI tract is suspected, different testing methods may be used to identify and differentiate between oocysts and trophozoites.

The choice of solution as well as method of analysis contributes to the success or failure of accurate analysis.Table 2lists fecal flotation solutions and the parasites identified through their use.1

Based on the SG differences of the various parts of a fecal sample (feces, ova, cysts, debris), the recovered eggs are lighter (ie, lower SG) than the flotation solution and will float to the surface. The heavier fecal matter (ie, higher SG) sinks rapidly.

Therefore, the flotation solution must have a higher SG than the parasite eggs or cysts. It is important to note that while water may often be a part of a fecal flotation solution, pure tap water alone cannot be used because the eggs and oocysts are heavier, sinking in the tap water and remaining unidentified.

Passive fecal flotation is conducted by mixing fecal matter and flotation solution in a small vial to form a slurry; the vial is then filled until a positive meniscus forms (Figure 5). A cover slip is placed over the meniscus and left undisturbed for 10 minutes, which allows the eggs/cysts to float to the top (Figure 6). The cover slip is then placed on a microscope slide and scanned at low power for signs of ova or larvae.2

There are several centrifugal fecal flotation devices currently available that include a sieve to strain the mixture, which provides a cleaner sample for analysis; these devices include the Fecatector (butlerschein.com), Fecalyzer (vetoquinolusa.com), and Ovassay Plus (zoetis.com).

Numerous published studies have established that centrifugation is the preferred technique for parasite identification,3-6 and is, therefore, the technique recommended by most parasitologists. The centrifugal force allows a more rapid, efficient, and thorough separation of eggs/cysts and debris.

While not common, it is possible to identify some nematode ova by evaluating vomit using the same methodology as for fecal flotation. Likewise, vomit may also be scrutinized under a microscope to locate parasites common to the stomach.

Vomit flotation is useful when parasites, such asPhysalopteraspecies orOllulanus tricuspis, are suspected in dogs and cats.2Vomit flotation should also be included in the initial workup for companion animals that present with chronic vomiting.2

The fecal sedimentation test is used to detect ova that have a SG higher than commonly used flotation solutions and, therefore, do not readily float. This method may also be used for ova that will be distorted or destroyed in the presence of a super saturated salt solution.

The sedimentation test is most valuable for identifying fluke ova, which have a higher SG and are larger, denser, and heavier than other ova, and should be performed in suspected cases of infection.1Also, because some nongastrointestinal inhabitants, such asParagonimus kellicotti(lung flukes), may also shed ova in sputum or other internal fluids, microscopic examination should be considered.2

The Baermann testing method (often referred to as the Baermann technique) involves the concentration of nematode larvae from a fecal sample. Although this technique is useful for identification of most nematodal larval forms, it is the gold standard method of testing for suspected cases of lungworm infection.Table 4lists the most common lungworm species seen in domestic animals.7,8

Successful larval collection relies on the fact that most nematode species lack the ability to swim against gravity. When lungworms are present in the lower respiratory tract, larvae within the airways move with sputum to the pharynx where they are swallowed and later shed in the feces. Thus, in the case of lungworms, no eggs are found in the feces, only larvae.7While there are several variations to the treatment of the sample in terms of staining and observation, the basic principle for the Baermann technique remains rooted in the simple apparatus required.

Culturing fecal material is a useful technique when eggs or cysts cannot be properly distinguished or identified. Incubation of the culture at room temperature encourages larval hatching and allows for easy identification.2

As a confirmatory method of identifying protozoan trophozoites, the fecal smear may be stained. The stain allows identification of oocysts and trophozoites by highlighting protozoan internal structures.

Since the iodine stain will kill trophozoites, it is prudent to examine the fecal smear for motile organisms prior to staining; the motility of trophozoites is what renders them easily identifiable. Nonmoving organisms may be difficult to identify within the stained smear.1,2

Heartworms Diagnosis of heartworms is both simple and complex, and dominates veterinary parasitological research. A major focus of research involves identification of this parasite as early as possible postinfection in order to facilitate timely treatment.

For instance,Hepatozoonis transmitted by ingestion of infected ticks, most notablyAmblyomma maculatumandRhipicephalus sanguineus. It should be noted thatH americanumoccurs only in North America and is carried byA maculatum.Hepatozoonpresents on the surface of polymorphonuclear leukocytes as well as in skeletal muscle.9

Thebuffy coat methodisolates motile microfilariae within the buffy coat layer, which is seen in centrifuged hematocrit tubes of whole blood, located between the red blood cell layer and plasma. This method, while considered fast, requires more prep time than the methods mentioned above. It should not be relied upon for definitive diagnosis because microfilaria may be difficult to see.

Use ofenzyme-linked immunosorbent assay(ELISA) testing methods, such as the SNAP Heartworm Test or SNAP 4Dx Plus Test (idexx.com), are also useful for in-clinic detection of either antigen or antibody in patients with or without clinical signs of heartworm disease but no evidence of circulating microfilaria detected through manual examination of blood (due to lack of reproducing females at time of testing).

Testing for antigensproduced by parasites remains the most widely used method of detection with regard to heartworm disease as it is quick and economically feasible. It should be noted that more than 1 method is often used to confirm results, whether negative or positive.

Diagnosis of unicellular parasites is easily accomplished in a clinical setting by examination of a stained blood smear. The best samples to evaluate are those from animals with an acute infection. A more definitive diagnosis or confirmatory testing (such as in the case ofBabesia) may be achieved throughdiagnostic serologyas well as utilization ofdiagnostic laboratory services.

The gold standard for blood protozoan identification is Giemsa stain, but the quick-dip, 3-step systems also yield satisfactory results, of which several varieties are commonly used in clinical practice.9

There are several parasites restricted to the urinary system, such as the giant kidney worm (Dioctophyma renale) and bladder worm (Pearsonema plica). The presence of these parasites is most easily confirmed by identifying the presence of ova in urine.

Ova may be identified by examining urine sediment samples collected through cystocentesis. To avoid contamination, cystocentesis is preferred over clean catch, voided specimens. Prior to testing, sample integrity should be guarded to avoid outside contamination, such as contact with insects, pollen, or other environmental debris.2,9

Oreta M. Samples,RVT, MPH, DHSc, is the lead veterinary technician and adjunct instructor at Fort Valley State University in Fort Valley, Georgia. She also is an adjunct instructor in epidemiology at Kaplan University, which has several campuses throughout the U.S., and an adjunct assistant professor at St. Francis University in Loretto, Pennsylvania. Her research interests include veterinary parasitology and clinical pathology. Ms. Samples is a founding member of the Academy of Veterinary Clinical Pathology Technicians and an editorial board member for NAVTA. She received her degrees in veterinary technology from Fort Valley State University and her MS in public health and Doctorate in health sciences from Nova Southeastern University in Fort Lauderdale, Florida.

froth flotation process - detailed explanation with diagrams and videos

Froth flotation is one of the most popular operational processes for mineral beneficiation. In ore/mineral beneficiation, froth flotation is a method by which commercially important minerals are separated from impurities and other minerals by collecting them on the surface of a froth layer.

Flotation is the process of separation of beneficial minerals from a mixture by creating froth on which minerals separate out. This method of froth floatation is a method of mineral processing in which different minerals are separated selectively. Such ores containing multiple metals such as lead, copper and zinc can be selectively extracted by using froth floatation.

1. True floatation In this process minerals are selectively attached to froth. This process is very critical and important as the extraction of the valuable minerals is decided by this step only while the other two steps determine the separation efficiency between the mineral and the gangue.

An important criterion of separation of minerals by the froth floatation method is that the size of the particles of the ores must be very small equivalent to powder form. This is very important because the heavier and bigger particle would require a greater adhesive force without which they would no longer attach to the froth and settle down in the bottom. Thus separation will not be possible.

The process of froth floatation starts with the Comminution process in which the surface area of the ore is increased. First of all, the ores are crushed into very fine powder sized particles and mixed with water. The mixture obtained is called Slurry. A Collector which acts as a surfactant chemical is added to the slurry. This is done to enhance the hydrophobic nature of the mineral.

The slurry has now been converted into pulp. This pulp is added in the container filled with water and then air jets are forced into it to create bubbles. The required mineral is repelled by water and thus gets attached to the air bubbles. As these air bubbles rise up to the surface with mineral particles sticking to it, these are called froth. This Froth is separated and further taken for the next process of refining and extraction.

The basic principle applied in the process of Froth Flotation is the difference in the wetting ability of the ore and remaining impurities. The particles are categorised into two types on the basis of their wetting ability;

If the minerals are of Hydrophobic nature then only can get attracted toward froth and not with water. Once these minerals come to the surface, by the help of buoyant force applied on the froth, the particle-bubble contact will be intact only when there is the formation of a stabilized foam. The deciding factor of the stability of the froth is the strength of the attachment of the bubble to the mineral. This is calculated by the help of YOUNG-DUPRE EQUATION. This equation gives the relation between the strength of attachment and the interfacial energies.

A common industrial column cell consists of a long cylindrical tank fitted with a feed inlet pipe in the upper portion of the cylinder. Two launders are also connected, one internally and one externally to collect and separate the foam. In the lower portion of the cylinder, an outlet pipe is also connected to remove the slurry and the non -floating material. Pipes for proper drainage and many nozzles for re-pulping are also fitted in the lower section of the column.

Many obstructing panels are also fitted in the column to ensure proper and uniform mixing inside the tank. The number of such panels depend on the geometry and size of the tank. A gas bubble generator system which is utilized for the generation of the bubbles is also fixed at the bottom of the column. A froth washing system, whose purpose is to separate the impurities from the froth, is attached on the top of the tank.

These methods are extensively utilised for metals of low reactivity generally sulphur compounds. Sulphide ores can be easily wetted by the oils which will float on water. These minerals are first converted into a fine powder and then mixed with water. After that pine oil is poured into this slurry. Then Air bubbles are created by injecting high-pressure air. Thus the sulphide ore comes on the top with the froth and oil. The remaining gangue particles which did not dissolve in oil settle down. The foam is removed and taken for further processing. Thus the minerals are separated by the froth -flotation process. This method is extensively utilized for Copper sulphide, lead sulphide and Zinc sulphide.

In order to maintain uniform quality of froth and optimise the adhesive quality of the minerals different chemicals are required to be mixed in the slurry.some of such important chemicals are listed below.

A collector is such a type of organic compound that selectively attaches to the surface of the minerals and adds water repelling nature to the particles, a very critical factor for adhesion of mineral particles to the air bubble.

Non-Ionic collectors: These are simple hydrocarbon oils which are needed to increase the water-repelling nature of those minerals which have low hydrophobic strength such as coal. This is done by selective adsorption of oils by the minerals. Examples of non-ionic collectors are Fuel oil and Kerosene oil.

Anionic collectors: These collectors consist of a non-polar part and an ionic part in the anionic part of the compound while the cationic part has no important function enhancement of hydrophobic nature.

Examples of carboxylates are salts of oleic acid and linoleic acid. Soaps generally are more beneficial compared to other ionic collectors because they have a long chain of fatty acids and can easily dissolve in water. These anionic collectors can be used for the separation of ores of alkali metals and alkaline earth metals like calcium, magnesium, barium, strontium etc.

Cationic collectors: in such collectors, the cationic part of the compound plays a very important role in increasing the surface properties of the mineral. The ionic part is generally the nitrogen of the compound amines. They undergo physisorption and get bonded to the mineral through electrostatic force of attraction. Due to this reason these cationic collectors have low adhesive force.

Frothers These are the group of compounds which help to stabilize the foam. Apart from stabilizing the bubbles they also help in the effective removal of foam and separation of gangue. The desired properties of a typical frother are that it should be able to generate foam so that minerals can be separated. They must be easily soluble in water with a fair degree of homogeneity.

These reagents activate the mineral surface towards the action of the Collectors, by enhancing their chemical properties. Therefore, they are often called friends of collectors. Generally, they are the easily ionisable soluble salts which react with the mineral surface. A very common example of an activator is in the case of the Sphalerite ore in which zinc is easily separated by the formation of zinc -Xanthate.

These reagents deactivate the mineral surface towards the action of Collectors, by changing their chemical properties. Hence, they are also called the enemies of the Collectors. They increase the Selectivity of flotation, by preventing one mineral from flotation while allowing another mineral to float unrestricted.

pH is also a very important factor in the process of floatation. Even a slight change in the pH of the slurry can result in loss of productivity and efficiency of the operation. Thus to ensure the optimum use of the resources and production is maximum pH modifiers are used. Lime, Sodium carbonate, Sodium hydroxide and Ammonia are often used to maintain the basic nature of the slurry whereas Sulphurous and Sulphuric acids are used to maintain the acidic medium.

7 best dog life vests [2021 reviews]: canine safety while at sea!

Most dogs are great swimmers, but even the best paddlers cant swim for long, and should an unfortunate disaster occur while out at sea, your dog would have no better chance of swimming to safety than you would.

While even water-loving dogs should be equipped with dog life jackets, they are even more important for dogs with low body fat like greyhounds, senior dogs, brachycephalic breeds, and dogs with health or mobility issues.

Boating adventures arent the only times to put a life jacket on your doggo. Dogs can get tired and drown just like people do. In fact, there are thousands of dog deaths each year from dogs falling into swimming pools.

Of all the life jackets on the market, weve identified the ones detailed below as some of the best. Any of them should help keep your doggo safer while enjoying the water just be sure to pick one that suits the needs of you and your pet best.

About: The Ruffwear K9 Float Coat is the one of the highest rated dog life jackets on the market, thanks to its extreme quality and reliability. While it comes at a higher price point, its definitely well merited, as this canine life vest is top-notch quality.

This vest comes with strategically-placed closed cell foam panels, which lets your dog stay in his natural swimming position.The vests telescoping neck closure is adjustable, which helps allow for natural and comfortable canine movement.

Youll note that this jacket has additional flotation beneath your poochs belly to ensure he stays afloat. There are also no exposed straps or buckles, to avoid any chance of dangerous snagging. Lastly, we love that this vest has reflective trim this will make sure you can easily see your dog in the water, even at dusk or when waves get a bit choppy.

Owners were impressed with the quality of the material and the extra flotation underneath the dogs belly to keep the dog afloat. Many buyers were also very pleased that this vest isdesigned to have no exposed straps or buckles.

About: The HAOCOO Life Jacket is a high-quality life preserver that is available in a wide array of colors and styles. You can select a fairly standard life jacket shape if your pup prefers to keep things low-key, or you could choose from several fun and silly styles that resemble mermaids, sharks or lobsters. There are 15 different options in total.

Each of the styles features top-notch materials, as theyre all made from high-grade polyester oxford and nylon fabric, mesh fabric, and pearl cotton foam. Two belly straps and a chest strap (each of which features a quick-release clip) will keep the vest snuggly attached to your dog, and reflective strips are included to ensure your dog is easy to see.

A handle is also included on the back to make it easy to lift or help your dog into or out of the water, and a D-ring is situated on the back to give you a place to attach a leash or tether. The life jacket comes in seven different sizes:

The HAOCOO Life Jacket is a great option for many dogs, as it comes in a very wide variety of sizes, styles, and colors. Most owners reported that it was very well made, plenty buoyant and provided good value for your dollar.

There arent any obvious shortcomings, although a few owners experienced sizing issues. It is probably wise to err on the large side when picking your size, as several owners complained that the size they chose was too small for their pup.

We love that the Paws Aboard Canine Life Jacket provides a heavy duty velcro fastening system for your dogs belly and neck, along with adjustable straps. The flotation vest also has a top handle for pulling your dog up out the water.

While many customers feel very satisfied with the product, a few have mentioned the straps tearing with larger, heavier dogs. The Velcro belly straps may also not be ideal for breeds with lots of fur, as fur can get caught in the Velcro.

About: The Kurgo Surf n Turf Coat is an all-in-one jacket, serving as a life vest as well as a three-season shell jacket. The flotation layer can be removed to double as a waterproof jacket for your canine.Thats right, this flotation vest can also function as a rain jacket or light autumn coat!

It also bears mentioning that all Kurgo products are backed with a lifetime warranty, so you can ensure this vest will last a lifetime. Note that, while this dog PFD may be appropriate for shallow waters, wed suggest other life vestsfor heavier seas.

We love how many features this life vest comes with, including the handle, reflective trim, and dual D-rings. Most owners who tried the vest found that it worked as theyd hoped, fit well, and was quite durable.

About: The PetCee Quick-Release Life Jacket is a cute and affordable life jacket for dogs, which includes a pretty nifty feature: It has an extra float that rests under your dogs chin. This helps poor swimmers to keep their head above the surface while swimming around.

The PetCee Life Jacket relies on three different straps (two that wrap around your dogs belly and one that wraps around his chest) to stay in place, and each of the straps features a quick-release buckle making it easy to put on or take off.

Reflective trim is included with all of the color options to help make it easier to see your dog in low light. A D-ring is also located on the back of the life jacket, giving you an easy way to attach a leash to your dog.

The PetCee Quick-Release Life Jacket is a great option for dogs who have trouble keeping their head above water, thanks to the included chin float. It is also very affordable, while still being well made. Additionally, you can get this jacket in any of several fun styles and color patterns.

A few owners reported that their dog did not like the chin float. Additionally, this doesnt appear to be the most buoyant life jacket on the market, so it is probably best to try it out in the shallows and see how it works for your dog before heading to deeper waters.

About: The Onemore Choice Camo Life Preserver is a heavy-duty life jacket that features a unique camouflage print. This makes it a great choice for fowl-retrieving dogs, as itll help keep your dog hidden from the ducks or geese youre hunting.

This life preserver features three straps (one that goes around the chest and two that wrap around your dogs belly) are included, and each features a quick-release buckle to make it easy to put on or take off. The belly portion of the vest is made from breathable mesh to ensure your dog remains comfortable while wearing it.

A handle is stitched to the back, making it easy to help your dog get into or out of the water, and it also features a D-ring on the back, so you can clip your dogs leash to the vest. Reflective trim is attached to the vest to make your dog more visible in low-light conditions.

This is obviously a fantastic choice for hunting dogs, given its camouflage appearance, but it will also work for dogs who just want to go for a swim at the local pool. The included handle and D-ring leash attachment are both nice features, and the breathable mesh appears to help keep dogs more comfortable while wearing it.

Some owners complained that both the handle and D-ring would break if too much force was applied to them, so this is jacket is probably not great for heavy dogs or those who pull on their leash. A few owners also mentioned that they needed to cut away a bit of material to prevent the vest from rubbing their dogs skin in an area or two.

We cant blame you if youre feeling overwhelmed at this point all these life vests for dogs received great reviews. However, we feel we can most confidently recommend the Outward Hound andRuffwear K9 Float Coat.

Fitting your dog with a life jacket will help keep him safe but doing so isnt a magic bullet youll still need to embrace a few common-sense practices to reduce the chances of accidents or injuries and ensure that everyone goes home happy, tired and smiling.

Itll be much easier to put the life vest on your dog if you help instill a positive attitude about wearing the floatation device from the outset. This will also help your dog feel more comfortable wearing it, which will ensure he still has a great time while swimming around.

Ideally, youd start the introductions several days before heading to the beach or lake. In a calm place (like your living room), take the vest out of the package and hold it in front of your dog for a minute so he can smell it.

At first, just rest the vest on him loosely, give some treats, and then remove the vest after a few seconds. Slowly increase the time that the vest is on. Once your pooch seems pretty comfortable with the loose-fitting vest, connect the straps and cinch them up so they fit snuggly. Follow the same pattern as before by leaving the vest on 10-seconds or so (with treats dispensed), then removing, then putting on for 30 seconds, a minute, and so on.

Repeat the process again in a few hours or the next day. Do this as often as necessary (always giving plenty of positive reinforcement) until he becomes comfortable with the vest and doesnt mind donning it. At this point, you should be ready for the water.

If the straps are too loose, your dogs body may shift in the vest, which may make it difficult for him to swim with a natural motion. It will also increase the odds of him barrel rolling, and ending up upside down in the water, which is obviously a dangerous situation.

These types of vests are made for deep-water use, provide plenty of buoyancy, and usually feature fairly non-descript styling (although they may come in a variety of colors, theyll generally forego the shark fins and other fun embellishments).

On the other hand, some vests are designed to help your dog stay afloat, but they arent really intended as a true safety device. Many such vests feature cute or funny appendages, such as shark fins or mermaid tails, and theyre usually adorable.

But, youll want to test out the strength of the D-ring (as well as the associated stitching) before you rely on it to keep your dog from running out into traffic. The included D-rings are generally intended for light-duty use, so they may not be capable of withstanding your strong huskys pulling behavior.

This is also a great technique for dogs who stop listening once they start swimming sometimes they have so much fun swimming, they become rather disobedient. But with a tether, you can just drag them (gently) back to shore.

Just be sure to use caution when tying your dog to a tether while swimming. If the rope gets caught around your dogs legs or neck, he could become unable to swim or suffer an injury. Using a tether requires constant vigilance from the owner.

Some owners find that it is easier to keep the rope from entangling a dog by attaching something buoyant (such as a poodle noodle section) to the rope about 1- to 2-feet away from the ring. This isnt a foolproof technique, but it will keep the rope out of your dogs way to some extent.

Generally, its best to not use a tether if possible, as your dog getting tangled in it could be quite problematic. Some stinky treats are usually compelling enough to get most dogs back on board the boat or beach!

Even if you outfit your dog with the finest life jacket money can buy, he still requires supervision while swimming. Life jackets drastically reduce the danger associated with swimming, but they arent perfect, and dogs can still get into a bit of trouble while paddling around.

Its also a good idea to limit your dogs swimming to wide-open places, where he is surrounded by nothing but water. This will reduce the chances that hell run into something or become snagged. You may also want to consider a dog-friendly float so your dog has an area to rest between swim sessions!

For example, dogs often have trouble getting out of the pool (in fact, be sure to scroll down to check out our article about pool ramps, which are designed to help make it easier for your dog to get out of the pool). They can also become trapped by filter intakes or overflow drains.

Were pretty big fans of DIY projects, but given the fact that life jackets are safety devices, it is probably wiser to just purchase a commercially manufactured model rather than trying to make one yourself.

Wed stop short of saying that life jackets are mandatory for all supervised doggos whore enjoying the pool. But, theyre always a good idea especially for poor swimmers, like bulldogs, pugs, and others.

Dog life jackets should fit much like human life jackets should. They must be very snug to prevent them from twisting or shifting in the water, while still providing a comfortable fit and not causing any rubbing or abrasions.

Like those associated with most other commercial canine products, dog life jacket prices vary significantly. Generally speaking, youll have to spend at least $20 to $30 for a budget model, and high-end models may cost several times as much.

Realistically, a bargain-basement life jacket will probably only last your dog a year or so before the material begins to wear out or fray. But premium models will usually last several years, especially if you take good care of them.

You can help your dog get used to a life jacket in the same basic way youd get him comfortable with any other new garment. Start in your living room, and allow him to sniff the jacket and check it out, maybe while sharing a few tasty treats to build up a positive association. Then try to gently put it on him, but take it off after a few minutes. Repeat this as necessary until he seems comfortable and happy wearing it. At this point, you can move to the water and see how he does.

Youll need to consult the manufacturers guidelines to learn how to measure your dog for a specific life jacket. That said, most will rely on a neck-circumference, chest-circumference, and back- or body-length measurement. Some also have weight guidelines.

Life jackets are a good idea for all four-footers, but theyre most important for dogs who have deep chests or short faces (brachycephalic breeds). Dogs who are overweight may also struggle to swim, while dogs with exceptionally low body fat may not be terribly buoyant both types should be fitted with a life jacket before swimming. Finally, dogs with physical handicaps or injuries should wear a life jacket, as they may be incapable of swimming properly.

Some dogs take a while to get used to the feeling of wearing a life jacket. In such cases, theyll often freeze and just stare at you with a blank expression. Dont panic in such cases just be patient and reassuring, and your dog will likely learn to tolerate the vest and begin moving normally over time.

Refer to the manufacturers instructions for specific care requirements of any given vest. However, generally speaking, youll want to rinse the vest off in clean, fresh water after use, wipe away any stubborn dirt or debris with a cloth, and most importantly hang the jacket up in a shady place to dry completely. Only then should you put it in a storage container or closet.

Being its June of 21 now I realize this article is a bit old. I just wanted to put something out there that actually happened to us today with our 14 yr old retriever mix. He had ACL surgery last August. Where I live you dont get good boating weather until roughly right before Memorial Day weekend. Our dog has done tons of walking but not anything very stressful on his body. He swam a couple time yesterday and did fine. Today we didnt listen to the parent in us and brought him again today instead of letting him rest. He had been out one day prior a week before. We stopped once to let him pee and get in and cool off. All good. Very shallow sandy area. We then went to another spot about an hour later to let him swim. I thru the ball in and he went and got it but on the way in I could tell his head couldve been higher. And no way was he letting go of his tennis ball. I was on our boat and told my wife to watch him. I turned to grab our cooler to put on the beach and my wife yelled. The beach has a fairly steep incline and drops off pretty quick but theres still plenty of room where its still an incline but slightly. When I looked my wife was trying to hold him up. Apparently when he got out and walking along the beach his rear right leg gave out and while it was only about 8-12 deep, he went under on his side. I got to him and he was completely out of it. Tongue out, rear legs stiff and both pointed toward. I gave him a few thrusts up under where his ribs meet his chest. He came to but I didnt think he was going to. It seemed like forever. I dont know if he had a seizure and was out of it when he fell or if his leg gave out and with the incline, lost his balance and just didnt have the footing or strength in the sandy water to hold himself up. He has swam here 50 times over the years. But reading about theses jackets for dogs made me wonder if they wouldve helped much. If he had a life jacket and had a seizure in the shallower water I dont know if that wouldve got him back over upright if his legs were dragging on bottom. But the main thing that concerns me reading this article is what wouldve kept his airways open if he was unconscious? I saw the chin assist vests but if your dog has no control of his head would that keep his nose out of the water? I realize these arent everything you need. Thats why as you mentioned watch your pet. As with kids, it only takes a split second. Had we both had our backs turned this easily couldve turned out worse. But Im still concerned for animals that have seizures. Im not sure what itd look like if you needed the protection I described. Once they cant control their heads I dont know if any of these would work. I apologize this being so long. This honestly did happen to us today. It did happen once last summer, but some kids had him so tired and threw the ball out for him to get. Fortunately I was watching then because the water was over his head and I ran out and grabbed him. I think he was exhausted because I saw the whole thing. Your right! They cant swim forever like people think. Even the best water dogs.

Unfortunately, while life jackets are certainly helpful and provide an additional layer of protection, theyre not infallible particularly for dogs whore suffering from other health ailments, like epilepsy. In these cases, its just important that you watch your doggo like a hawk and be ready to intervene if he starts having trouble.

It is unfortunate, these are the best jackets you can find. Last year we opted for the outward hound Granby Ripstop Life Jacket. Why the put Ripstop in the name is beyond my comprehension as the jacket is literally coming apart at the seams. And for a dog at 80lbs and wet from swimming, you would think the handles would be suitable for handling the animal but think again, it is the very reason the seams are under increased tension. Now strictly speaking flotation-wise yes the jacket performs well. But if I had to do this all over I would have taken scissors to the handles and cut them clean off. Youll have to use some other means by which to get your dog out of the water, especially difficult when the dog has jumped overboard, but think twice before you use those handles riiiiiiip! Great article, just wish there was something actually worth the money in doggy aquatic gear, fact remains they just dont make things like they used to.

I think this is one of the most important information for me. And im glad reading your article. But wanna remark on few general things, The web site style is ideal, the articles is really nice : D. Good job, cheers

Your site is useful, but it would be nice to know where the life jackets are made. These days we are all supporting local. Are they made in Canada, USA, China????? Maybe you could add a little flag or made in tag to each pic so I dont waste a lot of time reading details when I wont buy. Thank you Sue

Hi Sue we already make sure to note local brands when it comes to dog food, but we dont usually maintain these standards for other products since the vast majority of all dog products (with the exception of foods, treats, and chews) and manufactured overseas. When dog products are made in the USA, we usually note that in their features.

Ive got a 1 y/o Labradoodle named Oliver. He LOVES water, but Ive always been afraid to take him in lakes or rivers. I think getting a vest like one of these will help with my anxiety around it! Thanks alot for this post.

Anyone know of any issues w/dogs getting too hot while using a K9 life vest? It can get hot at Lake Powell. I would hope if she gets too hot she would just get in the water, but after all she is a dog Thanks!

Good day i like your number 3 Paws Aboard life jackets, i have a small dog he is a x chi & fox terrier, he weighs about 8 kg, what size will he be and how much does this cost i live in Gauteng, South Africa.

Ive been thinking about getting one of these for years and maybe I should just go ahead and buy one. Haleys definitely a water dog and loves to fetch sticks at the lake or beach, but she doesnt stay in the water for very long.

It would be great to have one for the safety aspect, but Im thinking she might enjoy staying in the water longer if she didnt have to work so hard at paddling to stay afloat. Great review of these vests, thanks!

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platinum mining and refining | education

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Nuggets or grains of pure platinum can be found in nature, but more frequently, platinum is found alloyed with other metals, such as iron, copper, gold, nickel, and the other PGMs. The size of platinum grains or nuggets varies from small granules to pebbles weighing up to 20 pounds (9 kg) or more. When platinum is found in a pure state, it is called native platinum .

In contrast to gold, platinum nuggets are relatively inconspicuous. They have a dull grayish or blackish color but when you handle them, they can be distinguished by their extraordinary heft . When iron is present in the alloy, a platinum nugget can also be slightly magnetic, a diagnostic tool for evaluating new discoveries.

Native platinum and platinum alloys can be found in concentrated sand and gravel beds called placer deposits. The sand and gravel beds are created when old rock is eroded from its source and further ground into pieces as it is washed into streams and rivers. Most of the worlds placer platinum is found in Russia. In the 19th century, alluvial deposits in the Ural Mountains were heavily mined. However, these deposits have been stripped of their highest-grade ore and now account for less than one percent of the platinum production from Russia.

Over the past ten years, significant quantities of platinum have been produced from two alluvial deposits in the far eastern region of Russia: the Kondyor mine in Khabarovsk region and the Koryak mine in Kamchatka. Together these two operations produced 185,000 oz of platinum in 2005.

Mining platinum in placer deposits is a relatively simple process. Dredges scoop the platinum-bearing sand or gravel from riverbeds or mining pits. The material is washed until platinum grains or nuggets are captured and pulled from the surrounding material.

Platinum is also mined as an ore . Platinum ores such as sperrylite and cooperite may be mined when they are found in quantities that make extraction economically feasible. In other situations, platinum is obtained as a by-product when ores of other metals, such as copper and nickel, are refined.

Most of the mining for platinum ore occurs deep underground. To extract the mineral-rich materials, miners pack explosives into holes drilled in the rock and blast it into smaller pieces. The broken rock is then collected and transported to the surface for processing.

Refining platinum ore is a costly and laborious process. It can take from eight weeks to six months to process a batch of ore, and it can take up to 12 tons (11 tonnes) of ore to produce a single troy ounce of platinum.

In a process called flotation separation, air bubbles are blown through the mixture and carry platinum particles to the surface of the bath. The platinum-rich froth is skimmed from the bath and allowed to dry into a concentrated powder. One ton of dried powder may contain between 3 and 30 ounces (85 to 850 grams) of PGMs.

The dried powder is then heated to extremely high temperatures to remove impurities. Air is blown over the matte that remains after smelting to eliminate unwanted iron and sulfur. At this point, the PGM content of the matte is now about 50 ounces (1.4 kg) per ton.

Further chemical processing will remove any base metals remaining in the matte, such as copper and nickel. At this stage, the mineral concentrate contains about 15 to 20 percent PGMs. In the final stage, the mineral concentrate is treated with aqua regia to dissolve the platinum. The solution is filtered, purified, and burned to produce pure platinum metal.

Platinum deposits are located in only a few areas of the world. For every ten gold mines there is only a single platinum mine. All the platinum ever mined would fill a room no more than 25 feet square. Today, world platinum production hovers at about seven million troy ounces per year.

More than 70 percent of the worlds platinum supply comes from the Bushveld Complex in South Africas Transvaal. Platinum was discovered in this region in 1924, further fueling the worlds platinum craze.

Russia is the second largest producer of platinum. The Norilsk-Talnakh region of Siberia contributes 20 percent of the worlds platinum supply, which is retrieved from massive nickel-copper-palladium deposits some 1200 meters below the surface.Another six percent of the worlds supply comes from North America, where large deposits can be found in Montana, Alaska, and in Ontario, Canada.

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flotation cell - an overview | sciencedirect topics

The MAC flotation cell was developed by Kadant-Lamort Inc. It can save energy comparedto conventional flotation systems. The MAC flotation cell is mainly used in the flotation section of waste paper deinking pulping, for removal of hydrophobic impurities such as filler, ash,ink particles, etc. It can increase pulp whiteness and meet the requirements of final paper appearance quality. Table11.11 shows the features of MAC flotation cell. Kadants MAC flotation cell deinking system uses air bubbles to float ink particles to the cell surface for removal from the recycled material. The latest generation of the MAC cell deinking system incorporates a patented bubble-washing process to reduce power consumption and also fiber loss. It combines small, new, auto-clean, low-pressure injectors with a flotation cell. The function of injectors is to aerate the stock before it is pumped and sent tangentially to the top of the cell. The air bubbles collect ink particles in the cell and rise up to the top to create a thick foam mat that is evacuated because of the slight pressurization of the cell. The partially deinked stock then goes to a deaeration chamber and is pumped to the next stage. Here, the operation is exactly the same as for the first stage. This stage also has the same number of injectors and same flow (Kadant,2011). This operation is repeated up to five times for a high ink removal rate. Remixing of the air coming from downstream stages of the process helps the upstream stages and improves the overall cell efficiency. Adjustable and selective losses of fiberdepend on the application and technical requirements inks, or inks and fillers. The use of low-pressure injectors in the MAC flotation cell could save about 2530% of the energy used in conventional flotation systems (ECOTARGET,2009). The benefits of the MAC flotation cell are summarized in Table11.12.

Agitated flotation cells are widely used in the mineral processing industry for separating, recovering, and concentrating valuable particulate material from undesired gangue. Their performance is lowered, however, when part of the particulate system consists of fines, with particle diameters typically in the range from 30 to 100m. For example, it was observed difficult to float fine particles because of the reduction of middle particles (of wolframite) as carriers and the poor collision and attachment between fine particles and air bubbles; a new kinetic model was proposed [34].

As an alternative to agitated cells, bubble columnsused in chemical engineering practice as chemical reactorswere proposed for the treatment of fine particle systems. Flotation columns, as they came to be known, were invented back in the 1960s in Canada [35]. The main feature that differentiates the column from the mechanical flotation cell (of Denver type) is wash water, added at the top of the froth. It was thought to be beneficial to overall column performance since it helps clean the froth from any entrained gangue, while at the same time preventing water from the pulp flowing into the concentrate. In this way, it was hoped that certain cleaning flotation stages could be gained.

Let us note that the perhaps insistence here on mineral processing is only due to the fact that most of the available literature on flotation is from this area, where the process was originated and being widely practiced. The effect of particle size on flotation recovery is significant; it was shown that there exists a certain size range in which optimum results may be obtained in mineral processing. This range varies with the mineral properties such as density, liberation, and so on, but was said to be of the order of 10100m [36].

Regulating the oxidation state of pyrite (FeS2) and arsenopyrite (FeAsS), by the addition of an oxidation or reduction chemical agent and due to the application of a short-chain xanthate as collector (such as potassium ethyl xanthate, KEX), was the key to selective separation of the two sulfide minerals, pyrite and arsenopyrite [37]. Strong oxidizing agents can depress previously floated arsenopyrite. Various reagents were examined separately as modifiers and among them were sodium metabisulfite, hydrazinium sulfate, and magnesia mixture. The laboratory experiments were carried out in a modified Hallimond tube, assisted by zeta-potential measurements and, in certain cases, by contact angle measurements.

This conventional bench-scale flotation cell provides a fast, convenient, and low-cost method, based on small samples (around 2g), usually of pure minerals and also artificial mixtures, for determining the general conditions under which minerals may be rendered floatableoften in the absence of a frother (to collect the concentrate in the side tube) [38]. This idea was later further modified in the lab replacing the diaphragm, in order to conduct dissolved air or electroflotation testssee Section 3.

Pyrite concentrates sometimes contain considerable amounts of arsenic. Since they are usually used for the production of sulfuric acid, this is undesirable from the environmental point of view. However, gold is often associated with arsenopyrite, often exhibiting a direct relationship between Au content and As grade. There is, therefore, some scope for concentrating arsenopyrite since the ore itself is otherwise of little value (see Fig.2.2). Note that previous work on pyrites usually concentrated on the problem of floating pyrite [40].

In the aforementioned figure (shown as example), the following conditions were applied: (1) collector [2-coco 2-methyl ammonium chloride] 42mg/L, frother (EtOH) 0.15% (v/v), superficial liquid velocity uL=1.02cm/s, superficial gas velocity uG=0.65cm/s, superficial wash water velocity uw=0.53cm/s; (2) hexadecylamine, 45mg/L; pine oil, 50mg/L; EtOH, 0.025%; uL=0.84cm/s; uG=0.72cm/s; uw=0.66cm/s; (3) Armoflot 43, 50mg/L; pine oil, 50mg/L; EtOH, 0.025%; uL=0.84cm/s; uG=0.71cm/s; uw=0.66cm/s [39]. The pyrite (with a relatively important Au content of 21g/ton) was a xanthate-floated concentrate. The presence of xanthates, however, might cause problems in the subsequent cyanidation of pyrites when recovering their Au value, which perhaps justified the need to find alternative collectors. In general, the amines exhibited a behavior similar to that of the xanthates (O-alkyl dithiocarbonates). The benefit of the amine was in its lower consumption, as compared with the xanthate systems.

The arsenic content of the pyrite was approximately 9% (from an initial 3.5% of the mixed sulfide ore). The material was sieved and the75m fraction was used for the laboratory-scale cylindrical column experiments. The effect on metallurgical characteristics of the flotation concentrate of varying the amount of ferric sulfate added to the pulp was studied; three collectors were used and their performance was compared (in Fig.2.2). Both hexadecylamine and Armoflot 43 (manufactured by Akzo) exhibited an increased recovery but a very low enrichment, whereas 2-coco 2-methyl ammonium chloride (Arquad-2C) showed a considerable enrichment; a compromise had to be made, therefore, between a high-grade and a low recovery.

Electroflotation (electrolytic flotation) is an unconventional separation process owing its name to the bubbles generation method it uses, i.e., electrolysis of the aqueous medium. In the bottom of the microcell, the two horizontal electrodes were made from stainless steel, the upper one being perforated. The current density applied was 300 Am2. It was observed that with lime used to control pH, different behavior was observed (see Fig.2.3). Pyrite, with permanganate (a known depressant) also as modifier, remained activated from pH 5.0 to 8.0at 80% recovery, while it was depressed at the pH range from 9.0 to 12.0. A conditioning of 30min was applied in the presence of modifier alone and further 15min after the addition of xanthate. The pure mineral sample, previously hand collected, crushed, and pulverized in the laboratory, was separated by wet sieving to the45 to+25m particle size range.

Pyrite due to its very heterogeneous surface, consisting of a mosaic of anodic and cathodic areas, presents a strong electrocatalytic activity in the anodic oxidation of xanthate to dixanthogen. It is also possible that the presence of the electric field, during electroflotation, affected the reactions taking place. In order to explain this difference in flotation behavior thermodynamic calculations for the system Fe-EX-H2O have been done [41]. It was concluded that electroflotation was capable of removing fine pyrite particles from a dilute dispersion, under controlled conditions. Nevertheless, dispersed air and electroflotation presented apparent differences for the same application.

The size of the gas bubbles produced was of the order of 50m, in diameter [21]. Similar measurements were later carried out at Newcastle, Australia [42]; where it was also noted that a feature of electroflotation is the ability to create very fine bubbles, which are known to improve flotation performance of fine particles.

In fact, the two electrodes of a horizontal electrodes set, usually applied in electroflotation, could be separated by a cation exchange membrane, as only one of the produced gases is often necessary [43]. In the lower part/separated electrode, an electrolyte was circulated to remove the created gas, and in the meantime, increase the conductivity; hence having power savings (as the electric field is built up between the electrodes through the use of the suspension conductivity). Attention should be paid in this case to anode corrosion, mainly by the chloride ion (i.e., seawater).

Microorganisms have a tremendous influence on their environment through the transfer of energy, charge, and materials across a complex biotic mineralsolution interface; the biomodification of mineral surfaces involves the complex action of microorganism on the mineral surface [44]. Mixed cationic/anionic surfactants are also generating increasing attention as effective collectors during the flotation of valuable minerals (i.e., muscovite, feldspar, and spodumene ores); the depression mechanisms on gangue minerals, such as quartz, were focused [45].

Another design of a flotation cell which applies ultrasound during the flotation process has been developed by Vargas-Hernndez et al. (2002). The design consists of a Denver cell (Koh and Schwarz, 2006) equipped with ultrasonic capabilities of performing ultrasound-assisted flotation experiments. This cell is universally accepted as a standard cell for laboratory flotation experiments. In Figure 35.25, a schematic of the Denver cell equipped with two power transducers is shown operating at 20kHz. The ultrasonic transducers are in acoustic contact with the body of the flotation cell but are not immersed in the same cell. Instead, they are submerged in distilled water and in a thin membrane that separates the radiant head of the transducer from the chamber body. The floatation chamber has a capacity of 2.7l and is also equipped with conventional systems to introduce air and mechanical agitation able to maintain the suspension of metallurgical pulp. In the upper part of the cell there is an area in which the foam is recovered for analysis by a process called skimming. The block diagram of Figure 35.25 further shows that the experimental system was developed to do ultrasonic-assisted flotation experiments. The transducers operate at 20kHz and can handle power up to 400W. In the Denver cell an acoustic probe, calibrated through a nonlinear system and capable of measuring high-intensity acoustic fields, is placed (Gaete-Garretn et al., 1993, 1998). This is done in order to determine the different acoustic field intensities with a spatial scanner during the experimentation. Figure 35.26 shows the distribution of ultrasonic field intensity obtained by a spatial scanner in the central area of the flotation chamber. The Denver cell with ultrasonic capabilities, as described, is shown in Figure 35.27. The obtained results were fairly positive. For example, for fine particle recovery it worked with metallurgical pulp under 325mesh, indicating floating particles of less than 45m, and the recovery curves are almost identical to those of an appropriate size mineral for flotation. This is shown in Figure 35.28, where a comparison between typical copper recovery curves for fine and normal particles is presented. The most interesting part of the flotation curves is the increase in recovery of molybdenum with ultrasonic power, as shown in Figure 35.29. The increase in recovery of iron is not good news for copper mines because the more iron floating the lower grade of recovery. This may be because the iron becomes more hydrophobic with ultrasonic action. According to the experts, this situation could be remedied by looking for specific additives to avoid this effect. Flotation kinetics shown in Figure 35.30 with 5 and 10W of acoustic power applied also show an excellent performance. It should be noted that the acoustic powers used to vary the flotation kinetics have been quite low and could clearly be expanded.

Figure 35.28. Compared recovering percent versus applied power in an ultrasonic-assisted flotation process in a Denver cell: (a) fine and ultrafine particles recovering and (b) normal particles recovering.

These experiments confirm the potential of power ultrasound in flotation. Research on assisted flotation with power ultrasound has been also carried out by Ozkan (2002), who has conducted experiments by pretreating pulp with ultrasound during flotation. Ozkhans objective was to recover magnesite from magnesite silts with particles smaller than 38m. Their results show that under ultrasonic fields the flotation foam bubbles are smaller, improving magnesite recovery rates. When Ozkhan treated magnesite mineral with a conventional treatment the beneficial effect of ultrasound was only manifested for mineral pretreatment. The flotation performed under ultrasonic field did not show improvement. This was because power ultrasound improves the buoyancy of clay iron and this has the effect of lowering the recovery of magnesite.

Kyllnen et al. (2004) employed a cell similar to Jordan to float heavy metals from contaminated soils in a continuous process. In their experiments they obtained a high recovery of heavy metals, improving the soil treatment process. Alp et al. (2004) have employed ultrasonic waves in the flotation of tincal minerals (borax Na O710 B4 H2O), finding the same effects as described above, i.e., that power ultrasound helps in the depression of clay. However, the beneficial effect of ultrasound is weakened when working with pulps with high mineral concentration (high density), probably due to an increase in the attenuation of the ultrasonic field. Safak and Halit (2006) investigated the action mechanisms of ultrasound under different flotation conditions. A cleaning effect on the floating particles was attributed to the ultrasonic energy, making the particles more reactive to the additives put in the metallurgical pulp. Furthermore due to the fact that the solid liquid interface is weaker than the cohesive forces of the metallurgic pulp liquids, it results in a medium favorable to creation of cavitation bubbles. The unstable conditions of a cavitation environment can produce changes in the collectors and even form emulsions when entering the surfactant additives. In general, many good properties are attributed to the application of ultrasound in flotation. For example, there is a more uniform distribution of the additives (reagents) and an increase in their activity. In fact in the case of carbon flotation it has been found that the floating times are shortened by the action of ultrasound, the bubble sizes are more stable, and the consumption of the reagents is drastically lowered.

Abrego Lpez (2006) studied a water recovery process of sludge from industrial plants. For this purpose he employed a flotation cell assisted by power ultrasound. In the first stage he made a flotation to recover heavy metals in the metallurgical pulp, obtaining a high level of recovery. In the second stage he added eucalyptus wood cones to the metallurgical pulp to act as an accumulator of copper, lead, nickel, iron, and aluminum. The author patented the method, claiming that it obtained an excellent recovery of all elements needing to be extracted. zkan and Kuyumcu (2007) showed some design principles for experimental flotation cells, proposing to equip a Denver flotation cell with four power transducers. Tests performed with this equipment consisted of evaluating the possible effects that high-intensity ultrasonic fields generated in the cell may have on the flotation. The author provides three-dimensional curves of ultrasonic cavitation fields in a Denver cell filled with water at frequencies between 25 and 40kHz. A warming effect was found, as expected. However, he states that this effect does not disturb the carbon recovery processes because carbon flotation rarely exceeds 5min. They also found that the pH of tap water increases with the power and time of application of ultrasound, while the pH of the carbonwaterreagentsludge mixture decreases. The conductivity of the metallurgical pulp grows with the power and time of application of ultrasound, but this does not affect flotation. The carbon quality obtained does not fall due to the application of ultrasound and the consumption of lowered reagents. They did not find an influence from the ultrasound frequency used in the process, between 25 and 40kHz. They affirmed that ultrasound is beneficial at all stages of concentration.

Kang et al. (2009) studied the effects of preconditioning of carbon mineral pulp in nature by ultrasound with a lot of sulfur content. They found that the nascent oxygen caused by cavitation produces pyrite over oxidation, lowering its hydrophobicity, with the same effect on the change of pH induced by ultrasonic treatment. Additionally, ultrasound decreases the liquid gas interfacial tension by increasing the number of bubbles. Similar effects occur in carbon particles. The perfect flotation index increases 25% with ultrasonic treatment. Kang et al. (2008) continued their efforts to understand the mechanism that causes effects in ultrasonic flotation, analyzing the floating particles under an ultrasonic field by different techniques like X-ray diffraction, electron microscopy, and scanning electron microscopy techniques. In carbon flotation it is estimated that ultrasonic preconditioning may contribute to desulfurization and ash removal (deashing) in carbon minerals. Zhou et al. (2009) have investigated the role of cavitation bubbles created by hydrodynamic cavitation in a flotation process, finding similar results to those reported for ultrasonic cavitation flotation. Finally, Ozkan (2012) has conducted flotation experiments with the presence of hard carbon sludge cavitation (slimes), encountering many of the effects that have been reported for the case of metallurgical pulp with ultrasound pretreatment. This includes improved flotation, drastic reduction in reagent consumption, and the possible prevention of oxidation of the surface of carbon sludge. A decrease in the ash content in floating carbon was not detected. However, tailings do not seem to contain carbon particles. All these effects can be attributed to acoustic cavitation. However, according to the author, there is a need to examine the contribution of ultrasound to the probability of particlebubble collision and the likelihood of getting the bubbles to connect to the particles. The latter effects have been proposed as causes for improvements in flotation processes in many of the publications reviewed, but there is no systematic study of this aspect.

In summary, power ultrasound assistance with flotation processes shows promising results in all versions of this technique, including conditioning metallurgical pulp before floating it, assisting the continuous flotation process, and improving the yields in conventional flotation cells. The results of ultrasonic floating invariably show a better selectivity and an increase, sometimes considerable, in the recovery of fine particles. Paradoxically, in many experiments an increase has been recorded in recovering particles suitable for normal flotation. These facts show the need for further research in the flotation process in almost all cases, with the exception perhaps of carbon flotation. For this last case, in light of the existing data the research should be directed toward scale-up of the technology.

The concentrate obtained from a batch flotation cell changes in character with time as the particles floating change in size, grade and quantity. In the same way, the concentrate from the last few cells in a continuous bank is different from that removed from the earlier cells. Particles of the same mineral float at different rates due to different particle characteristics and cell conditions.

The recovery of any particular mineral rises to an asymptotic value R which is generally less than 100%. The rate of recovery at time t is given by the slope of the tangent to the curve at t, and the rate of recovery at time t1 is clearly greater than the rate at time t2. There is a direct relationship between the rate of flotation and the amount of floatable material remaining in the cell, that is:

The process is carried out in a flotation cell or tank, of which there are two basic types, mechanical and pneumatic. Within each of these categories, there are two subtypes, those that operate as a single cell, and those that are operated as a series or bank of cells. A bank of cells (Fig. 8) is preferred because this makes the overall residence times more uniform (i.e., more like plug flow), rather than the highly diverse residence times that occur in a single (perfectly mixed) tank.

FIGURE 8. Flotation section of a 80,000t/d concentrating plant, showing the arrangement of the flotation cells into banks. A small part of the grinding section can be seen through the gap in the wall. [Courtesy Joy Manufacturing Co.]

The purpose of the flotation cell is to attach hydrophobic particles to air bubbles, so that they can float to the surface, form a froth, and can be removed. To do this, a flotation machine must maintain the particles in suspension, generate and disperse air bubbles, promote bubbleparticle collision, minimize bypass and dead spaces, minimize mechanical passage of particles to the froth, and have sufficient froth depth to allow nonhydrophobic (hydrophilic) particles to return to the suspension.

Pneumatic cells have no mechanical components in the cell. Agitation is generally by the inflow of air and/or slurry, and air bubbles are usually introduced by an injector. Until comparatively recently, their use was very restricted. However, the development of column flotation has seen a resurgence of this type of cell in a wider, but still restricted, range of applications. While the total volume of cell is still of the same order as that of a conventional mechanical cell, the floor space and energy requirements are substantially reduced. But the main advantage is that the cell provides superior countercurrent flow to that obtained in a traditional circuit (see Fig. 11), and so they are now often used as cleaning units.

Mechanical cells usually consist of long troughs with a series of mechanisms. Although the design details of the mechanisms vary from manufacturer to manufacturer, all consist of an impeller that rotates within baffles. Air is drawn or pumped down a central shaft and is dispersed by the impeller. Cells also vary in profile, degree of baffling, the extent of walling between mechanisms, and the discharge of froth from the top of the cell.

Selection of equipment is based on performance (represented by grade and recovery), capacity (metric tons per hour per cubic meter); costs (including capital, power, maintenance), and subjective factors.

Among all processing industries, only in the ore and mining industries is the accent more on wear resistance than corrosion. In mining industries, the process concerns material handling more than any physical or chemical conversions that take place during the refining operations. For example, in the excavation process of iron ore, conventional conveyer systems and sophisticated fluidized systems are both used [16,17]. In all these industries, cost and safety are the governing factors. In a fluidized system, the particles are transported as slurry using screw pumps through large pipes. These pipes and connected fittings are subjected to constant wear by the slurry containing hard minerals. Sometimes, depending on the accessibility of the mineral source, elaborate piping systems will be laid. As a high-output industry any disruption in the work will result in heavy budgetary deficiency. Antiabrasive rubber linings greatly enhance the life of equipment and reduce the maintenance cost. The scope for antiabrasive rubber lining is tremendous and the demand is ever increasing in these industries.

Different rubber compounds are used in the manufacture of flotation cell rubber components for various corrosion and abrasion duty conditions. Flotation as applied to mineral processing is a process of concentration of finely divided ores in which the valuable and worthless minerals are completely separated from each other. Concentration takes place from the adhesion of some species of solids to air bubbles and wetting of the other series of solids by water. The solids adhering to air bubbles float on the surface of the pulp because of a decrease in effective density caused by such adhesion, whereas those solids that are wetted by water in the pulp remain separated in the pulp. This method is probably the more widely used separation technique in the processing of ores. It is extensively used in the copper, zinc, nickel, cobalt, and molybdenum sections of the mineral treatment industry and is used to a lesser extent in gold and iron production. The various rubber compounds used in the lining of flotation cells and in the manufacture of their components for corrosive and abrasive duties are:

Operating above the maximum capacity can cause the performance of flotation cells to be poor even when adequate slurry residence time is available (Lynch et al., 1981). For example, Fig. 11.21 shows the impact of increasing volumetric feed flow rate on cell performance (Luttrell et al., 1999). The test data obtained at 2% solids correlates well with the theoretical performance curve predicted using a mixed reactor model (Levenspiel, 1972). Under this loading, coal recovery steadily decreased as feed rate increased due to a reduction in residence time. However, as the solids content was increased to 10% solids, the recovery dropped sharply and deviated substantially from the theoretical curve due to froth overloading. This problem can be particularly severe in coal flotation due to the high concentration of fast floating solids in the flotation feed and the presence of large particles in the flotation froth. Flotation columns are particularly sensitive to froth loading due to the small specific surface area (ratio of cross-sectional area to volume) for these units.

Theoretical studies indicate that loading capacity (i.e., carrying capacity) of the froth, which is normally reported in terms of the rate of dry solids floated per unit cross-sectional area, is strongly dependent on the size of particles in the froth (Sastri, 1996). Studies and extensive test work conducted by Eriez personnel also support this finding. As seen in Fig. 11.22, a direct correlation exists between capacity and both the mean size (d50) and ultrafines content of the flotation feedstock. The true loading capacity may be estimated from laboratory and pilot-scale flotation tests by conducting experiments as a function of feed solids content (Finch and Dobby, 1990). Field surveys indicate that conventional flotation machines can be operated with loading capacities of up to 1.52.0t/h/m2 for finer (0.150mm) feeds and 56t/h/m2 or more for coarser (0.600mm) feeds. Most of the full-scale columns in the coal industry operate at froth loading capacities less than 1.5t/h/m2 for material finer than 0.150mm and as high as 3.0t/h/m2 for flotation feed having a top size of 0.300mm feeds.

Froth handling is a major problem in coal flotation. Concentrates containing large amounts of ultrafine (<0.045mm) coal generally become excessively stable, creating serious problems related to backup in launders and downstream handling. Bethell and Luttrell (2005) demonstrated that coarser deslime froths readily collapsed, but finer froths had the tendency to remain stable for an indefinite period of time. Attempts made to overcome this problem by selecting weaker frothers or reducing frother dosage have not been successful and have generally led to lower circuit recoveries. Therefore, several circuit modifications have been adopted by the coal industry to deal with the froth stability problem. For example, froth launders need to be considerably oversized with steep slopes to reduce backup. Adequate vertical head must also be provided between the launder and downstream dewatering operations. In addition, piping and chute work must be designed such that the air can escape as the froth travels from the flotation circuit to the next unit operation.

Figure 11.23 shows how small changes in piping arrangements can result in better process performance. Shown in Fig. 11.23 is a column whose performance suffered due to the inability to move the froth product from the column launder although a large discharge nozzle (11m) had been provided. In this example, the froth built up in the launder and overflowed when the operators increased air rates. To prevent this problem, the air rates were lowered, which resulted in less than optimum coal recovery. It was determined that the downstream discharge piping was air-locking and preventing the launders from properly draining. The piping was replaced with larger chute work that allowed the froth to flow freely and the air to escape. As a result, higher aeration rates were possible and recoveries were significantly improved.

Some installations have resorted to using defoaming agents or high-pressure launder sprays to deal with froth stability. However, newer column installations eliminate this problem by including large de-aeration tanks to allow time for the froth to collapse (Fig. 11.24a). Special provisions may also be required to ensure that downstream dewatering units can accept the large froth volumes. For example, standard screen-bowl centrifuges equipped with 100mm inlets may need to be retrofitted with 200mm or larger inlets to minimize flow restrictions. In addition, while the use of screen-bowl centrifuges provides low product moistures, there are typically fine coal losses, as a large portion of the float product finer than 0.045mm is lost as main effluent. This material is highly hydrophobic and will typically accumulate on top of the thickener as a very stable froth layer, which increases the probability that the process water quality will become contaminated (i.e., black water).

This phenomenon is more prevalent in by-zero circuits, especially when the screen-bowl screen effluent is recycled back through the flotation circuit, either directly or through convoluted plant circuitry. Reintroducing material that has already been floated to the flotation circuit can result in a circulating load of very fine and highly floatable material. As a result, the capacity of the flotation equipment can be significantly reduced, which results in losses of valuable coal. Most installations will combat this by ensuring that the screen-bowl screen effluent is routed directly back to the screen bowl so that it does not return to the flotation circuit. The accumulation of froth on the thickener, which tends to be especially problematic in by-zero circuitry, is also reduced by utilizing reverse-weirs and taller center wells, as this approach helps to limit the amount of froth that can enter into the process water supply. Froth that does form on top of the clarifier can be eliminated by employing a floating boom that is placed directly in the thickener (Fig. 11.24b) and used in conjunction with water sprays. The floating boom can be constructed out of inexpensive PVC piping, and is typically attached to the rotating rakes. The boom floats on the water interface and drags any froth around to the walkway that extends over the thickener, where it is eliminated by the sprays.

Column cells have been developed over the past 30 years as an alternative to mechanically agitated flotation cells. The major operating difference between column and mechanical cells is the lack of agitation in column cells that reduces energy and maintenance costs. Also, it has been reported that the cost of installing a column flotation circuit is approximately 2540% less than an equivalent mechanical flotation circuit (Murdock et al., 1991). Improved metallurgical performance of column cells in iron ore flotation is reported and attributed to froth washing, which reduces the loss of fine iron minerals entrained into the froth phase (Dobby, 2002).

The Brazilian iron ore industry has embraced the use of column flotation cells for reducing the silica content of iron concentrates. Several companies, including Samarco Minerao S.A., Companhia Vale do Rio Doce (CRVD), Companhia Siderrgica Nacional (CSN), and Mineraes Brasileiras (MBR), are using column cells at present (Peres et al., 2007). Samarco Minerao, the first Brazilian producer to use column cells, installed column cells as part of a plant expansion program in the early 1990s (Viana et al., 1991). Pilot plant tests showed that utilization of a column recleaner circuit led to a 4% increase in iron recovery in the direct reduction concentrate and an increase in primary mill capacity when compared to a conventional mechanical circuit.

There are also some negative reports of the use of column cells in the literature. According to Dobby (2002), there were several failures in the application of column cells in the iron ore industry primarily due to issues related to scale-up. At CVRD's Samitri concentrator, after three column flotation stages, namely, rougher, cleaner, and recleaner, a secondary circuit of mechanical cells was still required to produce the final concentrate.

Imhof et al. (2005) detailed the use of pneumatic flotation cells to treat a magnetic separation stream of a magnetite ore by reverse flotation to reduce the silica content of the concentrate to below 1.5%. From laboratory testing, they claimed that the pneumatic cells performed better than either conventional mechanical cells or column cells. The pneumatic cells have successfully been implemented at the Compaia Minera Huasco's iron ore pellet plant.

This chapter presents a novel approach to establish the relationship between collector properties and the flotation behavior of goal in various flotation cells. Coal flotation selectivity can be improved if collector selection is primarily based on information obtained from prior contact angle and zeta potential measurements. In a study described in the chapter, this approach was applied to develop specific collectors for particular coals. A good correlation was obtained between laboratory batches and large-scale conventional flotation cells. This is not the case when these results are correlated with pneumatic cell trial data. The study described in the chapter was aimed at identifying reasons for the noncorrelation. Two collectors having different chemical compositions were selected for this investigation. A considerable reduction in coal recovery occurred at lower rotor speeds when comparing results of oxidized and virgin coal. The degree to which a collector enhances flocculation in both medium- and low-shear applications and also the stronger bubble-coal particle adherence required for high-shear cells must, therefore, all be taken into consideration when formulating a collector for coal flotation.

advanced flotation technology | eriez flotation division

Eriez Flotation is the world leader in column flotation technology with over 900 installations. Columns are used for floating well-liberated ores. Typically they produce higher grade and have lower power costs than conventional cells. Applications include Roughers Scavengers Cleaners

Eriez Flotation is the world leader in column flotation technology with over 900 installations. Columns are used for floating well-liberated ores. Typically they produce higher grade and have lower power costs than conventional cells. Applications include

The HydroFloat fluidized bed flotation cell radically increases flotation recoveries of coarse and semi-liberated ores. Applications include: Split-feed flow-sheets Flash flotation Coarse particle recovery

The StackCell uses a 2-stage system for particle collection and froth recovery. Collection is optimized in a high shear single-pass mixing canister and froth recovery is optimized in a quiescent flotation chamber. Wash water can be used.

The StackCell uses a 2-stage system for particle collection and froth recovery. Collection is optimized in a high shear single-pass mixing canister and froth recovery is optimized in a quiescent flotation chamber. Wash water can be used.

The CrossFlow is a high capacity teeter-bed separator, separating slurry streams based on particle size, shape and density. Applications include: Split-feed flow-sheets with the HydroFloat Density separation Size separation

The rotary slurry-powered distributor (RSP) is used to accurately and evenly split a slurry stream into two or more parts, without creating differences based on flow, percent solids, particle size or density. Applications include Splitting streams for feeding parallel lines for any mineral processing application

The rotary slurry-powered distributor (RSP) is used to accurately and evenly split a slurry stream into two or more parts, without creating differences based on flow, percent solids, particle size or density. Applications include

Eriez Flotation provides advanced engineering, metallurgical testing and innovative flotation technology for the mining and minerals processing industries. Strengths in process engineering, equipment design and fabrication positionEriez Flotation as a leader in minerals flotation systems around the world.

Applications forEriez Flotation equipment and systems include metallic and non-metallic minerals, bitumen recovery, fine coal recovery, organic recovery (solvent extraction and electrowinning) and gold/silver cyanidation. The company's product line encompasses flotation cells, gas spargers, slurry distributors and flotation test equipment.Eriez Flotation has designed, supplied and commissioned more than 1,000 flotation systems worldwide for cleaning, roughing and scavenging applications in metallic and non-metallic processing operations. And it is a leading producer of modular column flotation systems for recovering bitumen from oil sands.

Eriez Flotation has also made significant advances in fine coal recovery with flotation systems to recover classified and unclassified coal fines. The group's flotation columns are used extensively in many major coal preparation plants in North America and internationally.

Eriez Flotation provides advanced engineering, metallurgical testing and innovative flotation technology for the mining and minerals processing industries. Strengths in process engineering, equipment design and fabrication positionEriez Flotation as a leader in minerals flotation systems around the world. Read More