Beneficiation methods of lithium minerals from hard rock ores were reviewed.Spodumene is currently the main source of lithium from ores.Flotation, DMS and magnetic separation are the main beneficiation methods.Similarities between lithium minerals and gangue makes beneficiation complicated.Significant research in lithium minerals other than spodumene is needed.
The demand for lithium minerals has increased considerably in recent years due to the application of lithium compounds in lithium ion battery technology, portable electronic gadgets and power storage systems. Spodumene is the main lithium bearing mineral which is currently being explored and processed due to its high lithium content and the extensive occurrence of deposits. This literature review focuses on the various techniques used in the beneficiation of lithium minerals from hard rock pegmatite ores. Dense media separation and flotation are the main beneficiation methods used for the separation of lithium minerals from ores. The close similarity in chemical and physical properties between lithium minerals and associated gangue minerals complicates the beneficiation of lithium minerals from ores. Surface chemistry of minerals, type of collector, pulp pH, chemical pre-treatment methods, and the presence of slimes play key roles in lithium minerals flotation. This review also deals with the beneficiation flowsheets employed at some of the larger lithium processing plants in the world. Spodumene from pegmatite deposits is expected to be the main source of lithium from ores at present although future sources would most probably include other minerals such as lepidolite, petalite, zinnwaldite, jadarite and hectorite.
The main method for beneficiation of copper-nickel sulfide ore is flotation, while magnetic separation and gravity separation are usually auxiliary beneficiation methods. When flotation of copper sulfide nickel ores, collectors and foaming agents for flotation of copper sulfide minerals are often used. A basic principle for determining the flotation process is that it is better to allow copper to enter the nickel concentrate, and to avoid nickel entering the copper concentrate as much as possible. Because the nickel in the copper concentrate is lost during the smelting process, the copper in the nickel concentrate can be completely recovered. The flotation of copper-nickel ore has the following four basic processes.
Directly use priority flotation or partial priority flotation process: When the copper content in the ore is much higher than the nickel content, this process can be used to select copper into a separate concentrate. The advantage of this process is that copper concentrate with low nickel content can be directly obtained.
mixing flotation of copper and nickel from the ore, and then separating low-nickel-containing copper concentrate and copper-containing nickel concentrate from the mixed concentrate. After the nickel concentrate is smelted, high nickel matte is obtained, and the high nickel matte is then subjected to flotation separation.
When the flotability of various nickel minerals in the ore is very different, after the mixed flotation of copper and nickel, then from the tailings Further recover nickel-containing minerals with poor floatability.
Copper is a harmful impurity in nickel smelting, and the copper grade in copper-nickel ore has industrial recovery value. Therefore, copper-nickel separation technology is an important topic in copper-nickel ore beneficiation. Copper-nickel separation technology is divided into two types: copper-nickel mixed concentrate separation and high matte separation technology. Generally, the former is used for copper-nickel minerals with relatively coarse grain size and not closely related to each other, and the latter is used for copper-nickel minerals with fine grain size and densely interspersed ore.
Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.
All available copper-bearing natural mineral aggregates are called copper mines. The high-grade copper concentrate can be obtained by the coarse grinding, roughing, scavenging of copper ore, then grinding and concentrating of coarse concentrate.
Due to the different types of ore, the nature of the ore is also different, so the beneficiation process needs to be customized. The specific process for selecting copper ore depends mainly on the material composition, structure and copper occurrence state of the original copper ore.
Before the beneficiation of copper ores, crushing and grinding are required. The bulk ores are crushed to about 12cm by a jaw crusher or a cone crusher. Then the crushed materials are sent to the grinding equipment, and the final particle size of the copper ore is reduced to 0.15-0.2mm.
Copper sulfide can be divided into single copper ore, copper sulfur ore, copper-molybdenum deposit, copper nickel, carrollite and so on. Basically, only flotation can be considered in its separation.
Almost all copper sulphide ores contain iron-bearing sulfides, so in a sense, the flotation of copper sulfide is essentially the separation of copper sulfide from iron sulfide. The common iron sulfide minerals in copper ore are pyrite and pyrrhotite.
1 Disseminated grain size and symbiotic relationship of copper and iron sulfide. Generally, pyrite has a coarse grain size, while copper ore, especially secondary copper sulfide, is closely associated with pyrite. Only when the copper ore is finely ground can it be dissociated from pyrite. This characteristic can be used to select copper-sulphur mixed concentrates, discard the tailings, and then grind and separate the mixed concentrate.
2 The influence of secondary copper sulfide minerals. When the secondary copper sulfide mineral content is high, the copper ions in the slurry will increase, which will activate the pyrite and increase the difficulty of Cu-S separation.
3 The influence of pyrrhotite. The high content of pyrrhotite will affect the flotation of copper sulfide. Pyrrhotite oxidation will consume the consumption of oxygen in the pulp. In severe cases, the copper minerals do not float at the beginning of flotation. This can be improved by increasing inflation.
Generally, copper is floated firstly and then sulfur. The content of pyrite in dense massive copper-bearing pyrite is quite high and high alkalinity (free CaO content> 600800g/m3) and high dosage of xanthine are often used to suppress the pyrite. There is mainly pyrite in its tailings with few gangues, so the tailings are sulfur concentrates.
For the disseminated copper-sulfur ore, the preferential flotation process is adopted, and the sulphur in the tailings must be re-floated. To reduce the consumption of sulfuric acid during the floatation and ensure safe operation, the process condition of low alkalinity should be adopted as far as possible.
It is more advantageous for copper sulfur ore containing less sulfur with copper easy to be floated. Carry out the bulk flotation firstly in the weakly alkaline pulp and then add lime to the mixed concentrate to separate the copper and sulfur in the highly alkaline pulp.
In semi-preferential bulk-separation flotation, Z-200, OSN-43 or ester-105 with good selectivity are used as collectors to float copper minerals firstly. The copper concentrate is then subjected to copper-sulfur bulk flotation and the obtained copper-sulfur mixed concentrate is subjected to separation flotation of floating copper and suppressing sulfur.
It avoids the inhibition of the easily floating copper under high lime consumption and does not require a large amount of sulfuric acid-activated pyrite. It has the characteristics of reasonable structure, stable operation, a good index and early recovery of target minerals.
3 The xanthate collector mainly plays the role of chemisorption together with the cation Cu (2 +), so minerals whose surface contains more Cu (2 +) minerals have a strong effect with the xanthate. The order of the effect is: chalcocite > covellite > porphyrite> chalcopyrite.
4 The floatability of copper sulfide minerals is also affected by factors such as crystal size, mosaic size, being original or secondary. The minerals with fine crystal and mosaic size are difficult to float. Secondary copper sulfide ore is easy to oxidize and more difficult to float than original copper ore.
As for the grinding and floating process, it is more advantageous to adopt the stage grinding and floating process for refractory copper ore, such as the re-grinding and re-separation of coarse concentrate, re-grinding and re-separation of bulk concentrate, and separate treatment of medium ore.
Copper oxide (CuO) is insoluble in water, ethanol, soluble acid, ammonium chloride and potassium cyanide solutions. It can react with alkali when slowly dissolving in ammonia solution. The beneficiation methods of oxidized copper ore mainly include gravity separatio, magnetic separation (see details on copper ore processing plant), flotation and chemical beneficiation.
Flotation is one of the commonly used mineral processing techniques for copper oxide ores. According to the different properties of copper oxide ores, there are sulphidizing flotation, fatty acid flotation, amine flotation, emulsion flotation and chelating agent-neutral oil flotation method.
Process flow: The dosage of sodium sulfide can reach 1~2kg/t during vulcanization. Because the film produced by vulcanization is not stable and is easy to fall off after vigorous stirring, and sodium sulfide itself is easily oxidized, sodium sulfide should be added in batches.
Besides, the vulcanization speed of malachite and azurite is relatively fast, so the vulcanizing agent can be directly added to the first flotation cell with no need to stir in advance during vulcanization and adjust the amount of vulcanizing agent according to the foam state.
Fatty acids and their soaps are mainly used as collectors of fatty acid floatation, also known as direct flotation. During flotation, water glass (gangue inhibitor), phosphate, and sodium carbonate (slurry regulator) are also usually added.
There is a practice of mixing vulcanization and fatty acid methods. Firstly float the copper sulfide and part of the copper oxide with sodium sulfide and xanthate, and then float the residual copper oxide with fatty acid.
For example, the ore in the Nchanga processing plant in Zambia contains 4.7% copper. The copper content achieved to 50% ~ 55% through flotation by adding 500g/t of lime (pH 9 ~ 9.5), 10g/t of cresol (foaming agent), 60g/t of ethylxanthate, 35g/t of amyl xanthate, 1kg/t of sodium sulfide, 40g/t of palmitic acid and 75g/t of fuel oil.
It is mainly to sulfurize the copper oxide mineral firstly and then add the copper accessory ingredient to create a stable oil-wet surface. Then, the neutral oil emulsion is used to cover the mineral surface, resulting in a strong hydrophobic floating state. In this way, the mineral can be attached to the foams firmly to complete the separation.
Many problems should be paid attention to in the flotation of copper ore, such as the length of the vulcanization time, whether to add sodium sulphide in batches and the proportion of chemicals. Here is a brief introduction.
1 The vulcanization time. Different ores require different vulcanization times. Generally speaking, it should be short rather than longer. The suitable vulcanization time is 1 to 3 minutes. After 6 minutes, the recovery rate and concentrate grade will decrease.
2 Add sodium sulfide in batches. The roughing time for processing the ore in the concentrator is about ten minutes, while the ore contains a large amount of carbonaceous gangue and the divalent sulfur ions disappear quickly in the slurry. So the effect of adding sodium sulfide in batches is better than that of adding it once.
3 Add sodium sulfide proportionally. Generally, copper oxide floats in the liquid at a slower speed, and reduce the number of cycles of the mineral in the flotation process can obtain a higher recovery rate. It is of great significance to study the distribution ratio of sodium sulfide among different operations to catch the mineral at the right time.
The chemical beneficiation method is often used for refractory copper oxide and mixed copper. For some copper oxide minerals with high copper content, fine mosaic size and rich sludge, the chemical beneficiation method will be used to obtain good indicators because the flotation method is difficult to realize the separation.
The solution of ammonia and ammonium carbonate in a concentration of 12.5% was used as the solvent to leach for 2.5h at a temperature of 150, a pressure of 1925175~2026500Pa. The mother liquor can be distilled by steam at 90 to separate ammonia and carbon dioxide. Copper, on the other hand, is precipitated from the solution as black copper oxide powder.
Because some copper oxide minerals are not tightly combined with iron, manganese, etc., it is difficult to separate them by using the magnetic separation method alone, and flotation has a good separation effect.
Therefore, the flotation method is used to obtain high-grade concentrates, the magnetic separation is for tailings and wet smelting is carried out finally. This process combines flotation, magnetic and wet smelting very well, which greatly increases the recovery rate and reduces the beneficiation cost.
The above are several common beneficiation methods for copper oxide minerals. For the selection of copper oxide minerals, it is best to conduct a professional beneficiation test and customize the process according to the report.
Flotation is the most widely used method in copper mine production. The copper ore pulp is stirred and aerated, and the ore particles adhere to the foams under the action of various flotation agents. The foams rise to form a mineralized foam layer, which is scraped or overflowed by the scraper. This series of flotation processes are all completed in the flotation machine. (Contact Manufacturer)
The internal magnetic system of the barrel adopts a short circuit design to ensure that the barrel skin has no magnetic resistance at high speeds, and the stainless-steel barrel skin does not generate high temperatures, extending the life of the magnetic block.
Since it adopts a dynamic magnetic system design, the roller does not stick to the material, which is conducive to material sorting. The selected grade can be increased by 3-6 times to more than 65%.
Copper mines are generally purified by flotation, but for the beneficiation of copper minerals with coarser grain size and higher density, the pre-selection by the gravity separation method will greatly reduce the cost and achieve flotation indicators.
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Mans quest for musical expression is amply documented and dates back to ancient times. The desire for new ways of creating or rendering music has led to several inventions, ingenious and not quite so.
One of such inventions for musical expression is the Impempe whistle. Impempe is a Zulu word which Bryant explained, back in 1905, as tail-spine or quill of a porcupine by which it produces a rattling sound; quill or barrel, i.e. the bottom end, empty of pith, of any feather.
Impempe Whistle is an instrument of ancient origin having found a home in not only Celtic traditions, but Asian, African and American as well. It is known by many names, the most common ones being the Irish Whistle, Penny Whistle, Flageolet, Tin whistle and of course the Zulu name Impempe.
The kids from northern Transvaal would cut the whistle from reeds, which were readily available and also easy to cut to shape, using a flint or knife. Modern Impempe whistles are, however, made of aluminum. They have a brushed look. Impempe whistles come in fairly large and rounded, evenly spaced tone holes for moisture control and condensation.
In South Africa,Ian Turnbullappears to be the go-to man if you desire Impempe whistles worth the name. The tech nut has a company called, well, Impempe Whistles. It was the go-manufacturer of Impempe whistles, in different keys, in South Africa.
He started the company back in 2003 with a few prototypes. The company then evolved into manufacturer of professional Impempe whistles that clients vouch for across the world, from Germany to the United States.
With its most devoted advocate Ian Turnbull no longer updating the Impempe Whistles website, and also no longer updating thecompanys Facebook page, obtaining the whistles is becoming a difficult task and interest in the product has declined.
As a matter of fact, the official Impempe Whistles Facebook page was last updated in 2017 exactly three years ago; the companys website on which you are reading this now displayed just the company name and no information about the company or its products before now.
We have seen in some online forums and groups that people are still making use of the whistles and requesting for the whistles to be manufactured. These requests are probably not big enough to keep the business running, which could be the reason for the business shutdown. Since the whistle is not being manufactured anymore and people are still quite interested, we have decide to put up this medium as a source of information for those that would like to know about the whistle.
There has not been any official reason made available to the public as to why the company has stopped and we are not able to provide that information but what we know for sure is that there are some demand for iMpempe Whistles!. One curious and interested individual wrote on Reddit:
The modern Impempe Whistles made by Ian Turnbullare handcrafted Aluminium Whistles made of Aluminium with a curved windway, which helps deal with moisture and condensation. They come with a tuning slide which needs a touch of tuning slide grease or equivalent to help with a smooth slide and prevent from siezing.
The whistles are tuned with close attention to balance across the octaves as well as a comfortable reach for the fingers. Each whistle is tested and played before being shipped and ensured that it is in good order. After extensive development, the shaped windway brought about a change in the design with better intonation and focus but not losing the traditional Impempe sound.
Whistles were made into a variety of keys, and have whistles both Low and high, with a slightly different approach to both. The whistle is a great starting point for musical instruments and a great alternative to the traditional recorder. According to the makers, once you have mastered the whistle, the possibilities are endless.
It is a genuine musical instrument that has tugged many heart strings. Think of the Titanic movie theme, Braveheart etc. Come to think of it how about South Africas own Mango Groove, Big Voice Jack, and Spokes Mashiane. The whistle has a rich heritage in South Africa with the Kwela genre having brought a special happy, catchy vibe to the world but filled with history and destiny.
The company that made the whistle was situated in Hilton in the beautiful midlands of KwaZulu-Natal in South Africa. The misty mornings in the lush green foothills give one a sense of the Scottish landscape and the call of the fish eagle confirms the african-ness, bringing a blend of Celtic and African traditions which are epitomized in the Impempe whistle.
Of course, as stated at the outset, the use of whistle in music dates back to earliest times. In South Africa, even though its use has declined over time. Artistes are still exploring the whistle bend in music but they are pretty few.
Renei Solana is one such artiste. The songstress snapped the attention of South Africans recently when a video of her dancing to an Amapiano song and blowing an Impempe whistle went viral. She became a household name over night.
Given the charm of her performance, she was dubbed Whistle Girl, a name that has since stuck. Also, the songstress is now in demand as a feature artiste. She had linked up with Thelebe for the (impempe) whistle version of his song Jebson.
Perhaps because Amapiano is the genre that drew the attention of many to the charms of the Impempe whistles recently when Renei Solana performed an amapiano whistle challenge had erupted in Mzansi, with many participating.
Although Whistle Girl appears to have given Impempe whistles robust resonance, she wasnt the first to use the whistle in mainstream music. Notable musos had had Impempe whistle performances but didnt quite buzz like the Girl.
The test results of the automated mineral identification and characterization system (AMICS), including the mineral composition, particle size distribution, dissemination state and degree of liberation of the target minerals, could be used to improve the beneficiation process. Taking the Dalucao rare earth ore located in Dechang, Sichuan Province, China (with an average content of 2.40 wt%) as the research object in this paper, the chemical composition, phase composition and dissemination state of the minerals were tested by AMICS, and the minerals of different fineness were ground. The concentrate yield, grade and recovery rate of the minerals of different fineness were compared through flotation tests. When the grinding lasted for 5min and 82.60% of mineral grains passed through the 74-m sieve, the yield, grade and recovery rate could reach 20.19%, 8.75% and 73.64%, respectively (as the best grinding fineness), under the same flotation conditions.
Ling XX, Li QL, Liu Y. In situ SIMS Th-Pb dating of bastnaesite: constraint on the mineralization time of the Himalayan Mianning-Dechang rare earth element deposits. J Anal atom Spectrom. 2016;31(8):1680.
Wen LG, Zeng PS, Zhan XC, Fan CZ, Sun DY, Wang G, Yuan JH. Application of the automated mineral identification and characterization system (AMICS) in the Identification of rare earth and rare minerals. Rock Miner Anal. 2019;37(2):121.
Xu C, Kynicky J, Chakhmouradian AR, Li XH, Song WL. A case example of the importance of multi-analytical approach in deciphering carbonatite petrogenesis in South Qinling orogen: Miaoya rare-metal deposit, central China. Lithos. 2015;227:107.
Jiao, Y., Qiu, KH., Zhang, PC. et al. Process mineralogy of Dalucao rare earth ore and design of beneficiation process based on AMICS. Rare Met. 39, 959966 (2020). https://doi.org/10.1007/s12598-020-01446-w
Bauxite is a sedimentary rock that is rich in alumina, the base for making aluminum. It is generally easy to mine because it is found near the surface of terrain. However, the process for separating the alumina from the other base elements in bauxite can be environmentally unfriendly.
For bauxite refining the Bayer processthat separates the valuable alumina from the surrounding materials involves caustic materials, high temperatures, and pressure. The resulting waste stream, especially from bauxite, is a slurry generally known as red mud, that must be kept in holding ponds until the toxicity of the solution is neutralized. Red mud can have a severe environmental impact if holding ponds fail and the solution is released into local waterways.
To minimize the production of red mud and extract more alumina at the beginning of the process, ST Equipment & Technologys tribo-electrostatic belt separator can be used prior to the Bayer process to remove silicates from bauxite, and increase available alumina from finely ground bauxite. The result is the recovery of a greater amount of alumina, lower use of expensive caustic soda, a reduced need for red mud holding ponds, and a reduction in the amount of energy needed during the Bayer process to heat and pressurize the mined materials.
ST Equipment & Technologys belt separator is also extremely energy efficient, can process a large amount of feed material per hour, and is small enough to be used on-site at refining operations, reducing shipping costs.
In other words, youll be saving money on processing, making more money on the additional alumina youll be pulling from the feed material, and you can present your mining company as an eco-friendly operation, which goes a long way toward building a good reputation with the locals.
We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill. We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters, and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill. The results show that the optimum process parameters for the vertical roller mill are as follows: a grinding fineness of 81.6wt% of particles less than 0.074 mm, a dodecyl amine (DDA) dosage in magnesite reverse flotation of 100 gt-1, and dosages of Na2CO3, (NaPO3)6, and NaOL in the positive flotation section of 1000, 100, and 1000 gt1, respectively. Compared with the ball mill, the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28% increase in the concentrate grade of MgO and a 5.88% increase in the recovery of MgO. The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of low-grade magnesite.
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D. Misch, H. Pluch, H. Mali, F. Ebner, and H. Hui, Genesis of giant Early Proterozoic magnesite and related talc deposits in the Mafeng area, Liaoning Province, NE China, J. Asian Earth Sci., 160(2018), p. 1.
Q.Y. Sun, W.Z. Yin, D. Li, Y.F. Fu, J.W. Xue, and J. Yao, Improving the sulfidation-flotation of fine cuprite by hydrophobic flocculation pretreatment, Int. J. Miner. Metall. Mater, 25(2018), No. 11, p. 1256.
Y.F. Fu, Z.L. Zhu, J. Yao, H.L. Han, W.Z. Yin, B. Yang, Improved depression of talc in chalcopyrite flotation using a novel depressant combination of calcium ions and sodium lignosulfonate, Colloids Surf., A, 558(2018), p. 88.
L.R.D. Jensen, H. Friis, E. Fundal, P. Mller, P.B. Brockhoff, and M. Jespersen, Influence of quartz particles on wear in vertical roller mills. Part I: Quartz concentration, Miner. Eng., 23(2010), No. 5, p. 390.
K. Boussu, B. van der Bruggen, A. Volodin, J. Snauwaert, C.V. Haesendonck, and C. Vandecasteele, Roughness and hydrophobicity studies of nanofiltration membranes using different modes of AFM, J. Colloid Interface Sci., 286(2005), No. 2, p. 632.
Z. Xie, H. Jiang, Z.C. Sun, and Q.H. Yang, Direct AFM measurements of morphology and interaction force at solid-liquid interfaces between DTAC/CTAC and mica, J. Cent. South Univ., 23(2016), No. 9, p. 2182.
D. Li, W.Z. Yin, J.W. Xue, J. Yao, Y.F. Fu, and Q. Liu, Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate, Int. J. Miner. Metall. Mater, 24(2017), No. 7, p. 736.
S. Rahimi, M. Irannajad, and A. Mehdilo, Effects of sodium carbonate and calcium chloride on calcite depression in cationic flotation of pyrolusite, Trans. Nonferrous Met. Soc. China, 27(2017), No. 8, p. 1831.
C. Liu, Q.M. Feng, G.F. Zhang, W. Chen, and Y.F. Chen, Effect of depressants in the selective flotation of scheelite and calcite using oxidized paraffin soap as collector, Int. J. Miner. Process., 157(2016), p. 210.
A. Ramirez, A. Rojas, L. Gutierrez, and J.S. Laskowski, Sodium hexametaphosphate and sodium silicate as dispersants to reduce the negative effect of kaolinite on the flotation of chalcopyrite in seawater, Miner. Eng., 125(2018), p. 10.
Q.C. Feng, S.M. Wen, W.J. Zhao, and Y. Chen, Effect of calcium ions on adsorption of sodium oleate onto cassiterite and quartz surfaces and implications for their flotation separation, Sep. Purif. Technol, 200(2018), p. 300.
R.J. Zheng, Z.J. Ren, H.M. Gao, Z.J. Chen, Y.P. Qian, and Y.B. Li, Effects of crystal chemistry on sodium oleate adsorption on fluorite surface investigated by molecular dynamics simulation, Miner. Eng., 124(2018), p. 77.
X.M. Luo, Y.F. Wang, M.Z. Ma, S.X. Song, Y. Zhang, J.S. Deng, and J. Liu, Role of dissolved mineral species in quartz flotation and siderite solubility simulation, Physicochem. Probl. Miner. Process., 53(2017), No. 1, p. 1241.
L.Y. Liu, F.F. Min, J. Chen, F.Q. Lu, and L. Shen, The adsorption of dodecylamine and oleic acid on kaolinite surfaces: Insights from DFT calculation and experimental investigation, Appl. Surf. Sci., 470(2019), p. 27.
P.Y. Xu, J. Li, C. Hu, Z. Chen, H.Q. Ye, Z.Q. Yuan, and W.J. Cai, Surface property variations in flotation performance of calcite particles under different grinding patterns, J. Cent. South Univ., 25(2018), No. 6, p. 1306.
L.H. Xu, Y.H. Hu, H.Q. Wu, J. Tian, J. Liu, Z.Y. Gao, and L. Wang, Surface crystal chemistry of spodumene with different size fractions and implications for flotation, Sep Purif. Technol, 169(2016), p. 33.
Li, C., Sun, Cy., Wang, Yl. et al. Research on new beneficiation process of low-grade magnesite using vertical roller mill. Int J Miner Metall Mater 27, 432442 (2020). https://doi.org/10.1007/s12613-019-1898-2
In the mineral industry, beneficiation is a process which is designed to improve the yield from a deposit of ore. This increases the potential profits available from the ore, and allows a company to increase the overall profitability of a mine and its business in a particular area. A number of processes are used to accomplish beneficiation objectives, and several companies which make mining equipment have lines of products which are designed to help companies get more out of their ore.
The goal of beneficiation is to eliminate inefficiency and waste by ensuring that as much recoverable material as possible is extracted from ore. A number of techniques can be used for this, often starting with grinding the ore into particles. Once ground, the particles can be sifted and sorted to extract usable material and set waste aside. For example, the particles may be suspended in water to allow various components to separate out, making it easy to access usable ore.
For rare resources, beneficiation is critical, because it takes advantage of every scrap of material available. This practice can also make a marginal mining facility more practical than it might otherwise be, and may in fact be used to extract ore from a facility previously believed to be exhausted. The potential for beneficiation is also considered when evaluating sites of prospective mines, to determine whether or not the expense of mine operation will be outweighed by the products of the mine.
People concerned with sustainable development and ethical business practices also use the term beneficiation, but in a slightly different way. Rather than meaning that the maximum potential of a resource has been exploited, beneficiation refers to business practices which benefit the communities where products are mined, harvested, and otherwise taken. Historically, major companies have tended to enter small communities, take resources, and then leave, with no benefit to the populace.
This practice of exploiting a community and then leaving has become frowned upon as a form of exploitation of people and national governments, making beneficiation increasingly popular. With beneficiation, a company does things like moving some of its operations to the country where a product is harvested or mined, giving back to the community, and doing more work to keep some of the profits and benefits in country. For example, if a company is mining opals, it might open a facility for cutting and polishing opals near the mine, rather than shipping them overseas for processing, to create more job opportunities for the local community. Likewise, a company taking timber might operate a mill near the forest rather than shipping raw timber overseas.
Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.
Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.
Economic and operating conditions make it important to provide a simple, low cost, efficient method for recovering fine coal from washery waste. Not only is the water pollution problem a serious one, but refuse storage and disposal in many areas is becoming limited and more difficult. Many breakers and washeries efficiently handle the coarser sizes, but waste the coal fines. This problem is assuming major importance due to the increase in the amount of coal fines being produced by the mechanization of coal mining.
Flotation offers a very satisfactory low-cost method for recovering a fine, low ash, clean coal product at a profit. Often this fine coal, when combined with the cleaned, coarser fractions, results in an over-all superior product, low in ash and sulphur, giving maximum profit returns per unit mined.
Generally a very simple flotation flowsheet, as illustrated above, will be suitable for recovering the lowash coal present in waste from coarse recovery washeries.Assuming the fines are approximately all minus 20 mesh and in a water slurry of about 20% to 25% solids, the first step is to condition with a reagent which will promote flotation of the fine coal particles. Kerosene, fuel oil, coal tars and similar hydrocarbons will accomplish this effectively when added to thecoal slurry in a (Patented) Super Agitator and Conditioner. A frothing agent such as pine oil, alcohol frother, or cresylic acid added to the slurry as it discharges from the conditioner is also used. The separation between low ash coal and high ash refuse is efficiently accomplished in a Sub-A Flotation Machine. As the amount of clean coal floated represents a high percentage of the initial feed, provision is made to remove the cleaned coal from both sides of the cell. Fine coal is dewatered with a Disc Filter, as the Flotation Machine can usually be regulated to produce a product low in ash and with proper density for direct filtration.
It is highly desirable to extend the range of coal flotation to include the coarser Sizes. Not only will this simplify general washery practice but will result in a superior product having desirable marketing characteristics for metallurgical and steam power plant uses. It is now possible to efficiently recover coal by flotation through the entire size range beginning at about 4 mesh down to fines, minus 200 mesh.
With the flowsheet as outlined for coarse coal recovery, the feed is first deslimed for removal of high ash slimes and excess water. The hydroclassifier underflow is conditioned at 40% to 45% solids with kerosene or fuel oil and diluted with water to 20%-25% solids prior to flotation. If pyrite and coarse high ash material are present, it is often helpful to pass the conditioned pulp over a Mineral Jig for removal of a portion of these impurities. Hindered settling in the jig against a rising pulsating water column classifies out the high gravity impurities and eliminates them from the flotation circuit. Water requirements are low and feed density to flotation can easily be maintained at the proper level.
The Sub-A (Lasseter Type) Flotation Machine has proved successful for treating coarse coal with the flowsheet as indicated. A frother of the alcohol type is generally added to the flotation feed after conditioning with kerosene. Floated coal will collect in a heavy dense matte at the cell surface and as raked off, will contain up to 60% solids. Mechanical dewatering is usually not necessary. Natural drainage, dewatering on porous bottom screw conveyors, and vibrating screen dewatering are all being used successfully in coarse coal recovery circuits.
Flotation, with the Sub-A gravity flow principle, provides the ideal way to treat coal fines even as coarse as 3/16 top size. According to reports from plants operating for the production of metallurgical coke, each percent ash in the coal carries a penalty of 2$ per ton of coal. Thus there is a considerable margin for operating costs in a fine flotation cleaning method that will materially lower the ash of the cleaned coal. Further convincing evidence that ash removal from coal is of major importance is found in the weekly magazine of metal working, Steel, January 29, 1951, reporting on a modern coal preparation plant. The report states that a 1% reduction in ash content of coal means a reduction of 30 cents in cost of pig iron. One large plant reduces the ash from 7% to 3.5% by cleaning, thus cutting the cost of producing pig iron a dollar or more per ton.
A coal flotation machine must not only be able to handle a coarse as well as a fine feed, but it must also be simple to operate. Gravity circulation permits the treatment of difficult unclassified feeds.
High cost of mining makes it very important from a profit standpoint to recover all of the low ash coal, both coarse and fines. With the present trend toward mechanization, more fines are produced in mining. In many operations it is no longer economical to discard these fines to waste even though ash contiminants render the fines unmarketable without additional cleaning.
Water conservation, stream pollution and refuse storage are also factors which must be taken into consideration along with marketing requirements for the clean coal product. Flotation offers an efficient and low-cost method for recovering coal fines at a profit. In many cases floated coal fines can be blended with the coarser fractions without affecting ash, moisture or size limitations. This is being done successfully in coking coal operations. Fine coal is also being used extensively in steam plants for electric power generation.
The above flowsheets are based on existing small coal flotation plants. They illustrate clearly the simplicity and feasibility of adding Sub-A Coal Flotation as an additional process to small washing plants.
Because of its limited output, treatment must be very simple and operating costs kept to a minimum. At the washery, illustrated by flowsheet A, the entire mine output is sold for coking coal. Mining the relatively narrow seam produces a product with 15 to 20% ash, although the coal when cleaned will carry only 3 to 3% ash. This low ash coal brings a premiumprice, so it is an economic necessity to remove the impurities.
The mine run coal is crushed to a size for coking coal requirements. The entire production is treated over a coal jig which removes as waste primarily the coarse refuse. The coarse clean coal passes over the jig along with the fines and is elevated to a wedge bar stationary screen with 1 millimeter openings for dewatering. The coarse clean coal passing over the screen discharges by gravity into a storage bin. The fine coal, along with clay and its high ash fractions and water averaging 15 to 18% solids, discharges by gravity into a (Patented) Super Agitator and Conditioner. Kerosene and pine oil are added and the conditioned slurry or pulp then is introduced into the Sub-A Coal Flotation Machine.
The low ash coal product removed from the Sub-A Coal Flotation Cells contains 35 to 40% solids and is transferred to the coarse coal storage bin through a Vertical Concentrate pump. The flotation coal mixes with the coarse product which allows for adequate drainage and minimum loss of fines.
In the operation as illustrated by flowsheet B, approximately 15 tons per hour of coal flotation concentrate are produced. This installation requires more control to meet specifications and consequently a more elaborate system is necessary.
Screen undersize and water containing fines from the gravity separator are thickened in a centrifugal or cyclone separator to give the proper water-to-solids ratio for subsequent treatment. The effluent from the cyclone contains collodial slimes and high ash fines in addition to the bulk of the water from screening and gravity systems. Thickened coal fines from the cyclone pass over a Mineral Jig which removes a high ash refuse and free pyrite down as fine as 150 to 200 mesh.
The coal fines passing over the Jig are conditioned with reagents in the (Patented) Super Agitator and Conditioner and subjected to flotation treatment in a 6-cell Sub-A Coal Flotation Machine at approximately 20-25% solids. Double overflow of froth is used due to the low ratio of concentration and the high weight percentage of floatable coal recovered by flotation.
The coal flotation product at 35% solids is dewatered by a Disc Filter. Coarse coal from the gravity section and fine coal from the flotation section are blended and transferred by rail to the coke plant.
In some cases the coarse and fine coal are dewatered by Dillon Vibrating Screens. The coarser fractions of coal are first added to the screen to form a bed and flotation fines are added on top of this bed for dewatering. Where operating conditions are favorable, this system is preferred to other means of dewatering as it assures a well blended product low in moisture and uniform in ash content.
Effluent from the cyclone, high ash jig refuse and flotation tailing refuse are thickened in a Thickener to conserve and re-use water. Thickener refuse is disposed of without contaminating local streams.
Sub-A Coal Flotation with its gravity flow principle and selective action makes it possible to recover low ash coal from 1/8 down to minus 200 mesh. If an appreciable amount of recoverable coal is plus 20 mesh in size, the Sub-A Lasseter Type Coal Flotation Machine should be used. It is no longer necessary to use a complex system for fine coal recovery. Flotation will effectively handle the entire fine size range at low cost and produce a low ash marketable product.
In the washing of coal the problem exists in having to clean the fines in an economical and efficient manner without an excessively complex flowsheet. Mechanized mining creates fines not considered as problems in older methods of selective mining and underground loading. In many cases the minus 1/8 inch fines require cleaning to lower the ash content and frequently it is also necessary to reclaim all of the water for re-use in the washing system. Most plants use a closed water system to conserve water and comply with anti-stream pollution regulations.
Flotation offers a means for handling the entire size range minus 1/8 inch x 0. Efficient recovery of the fines at a low ashcontent is accomplished in a relatively simple flowsheet. Thesubstantial amount of coarser sizes in the concentrates aids in subsequent dewatering either by vacuum filters or dewatering screens.
In the flowsheet shown mine run coal after proper size reduction treatment is passed over heavy duty screening equipment to removethe minus 1/8 inch fines. Wet screening down to 10 or 12 mesh offers no particular problem. Water sprays are generally employed to thoroughly wash the fines from the coarse coal and prepare it for treatment. A surge tank or a thickener ahead of the conditioning and flotation section may be necessary to provide a uniform feed rate both as to solids content and density.
The coarse coal is washed and up graded in a conventional manner through heavy media or coal jigs to produce a clean coal and a coarse refuse. Any fines due to degradation through the coarse cleaning system is collected, partially dewatered and combined with the fines from the screening section.
Minus 1/8 inch x 0 coal fines are conditioned with the required amount of fuel oil or kerosene (approximately 1 to 3 lbs/ton) to thoroughly activate the low ash coal particles and render them floatable. Density in the conditioner should be as high as possible; however, for the open circuit system as shown it very likely will be maintained between 20 to 25% solids. A Super Agitator and Conditioner is preferred for this service since any froth accumulation on the surface is drawn down the standpipe and thoroughly dispersed throughout the pulp. This also aids in the most effective use of reagents.
The discharge from the conditioner at 20% solids is floated in a Sub-A Flotation Machine of the free flow type for handling coarse solids. Some dilution water may be necessary to maintain the feed density at 20% solids. A frother such as pine oil, cresylic acid, or one of the higher alcohols is added to the head of the flotation circuit at the rate of about 0.5-1.5 lbs/ton.
In the primary flotation section a high recovery of the coal fines minus 28 mesh is secured. In addition some of the more readily floatable coarse coal, low in ash, is also recovered. However, ability of the machine to handle all 1/8 inch feed permits recovery of coal over wide range of mesh sizes, thus improving filtering and handling characteristics. This coal, if not clean enough, is refloated in cleaner cells and middlings are recycled back to the feed. Clean coal will contain about 35% solids which is ideal for vacuum filtration. A Agitator Type Disc Filter is used as solids are effectively kept in suspension giving uniform distribution of cake for greater dewatering.
Generally the refuse from the primary flotation cells will contain a very high ash content in the -28 or-35 mesh size fraction. By screening the refuse the excess water and undersize high ash fines are eliminated while screen oversize is re-treated by flotation. This screening need not be highly efficient since only a partial sizing is satisfactory. Handling the coal in this manner reduces size degradation to a minimum.
The coarse coal from the foregoing dewatering and screening step is repulped to about 40% solids and conditioned with reagents. The conditioned pulp after dilution to 25 to 28% solids is floated in a second bank of flotation cells. The coarse coal in the absence of fines will form a dense, heavy matte at the surface of the cells. For this type of flotation, slow moving rakes are provided to remove the coal as final concentrate. This clean coal will generally contain over 50% solids, thus making it ideal for dewatering over vibrating screens or on a horizontal or top feed vacuum filter. In some plants where moisture is not too critical a screw conveyor with wedge bar bottom sections is used for the dewatering step.
The refuse from the coarse coal flotation cells may still contain some coal notresponsive to flotation recovery but low enough in ash to be saved. In such cases the refuse can be screened and the oversize fraction jigged or tabled. The tonnage at this point is usually only a very small percentage of the initial fines so the equipment requirements for this gravity section are moderate.
All refuse in the 1/8 inch x 0 coal recovery section is collected in a thickener for water reclamation. The thickened refuse or sludge underflow may be pumped to waste ponds, or if water is in short supply, filtration of this refuse may be necessary.
Coal flotation concentrates produced in this primary section are filtered direct and the filtrate is re-cycled back to the flotation cells for re-use. This filtrate is high in reagent content and is particularly useful as dilution water. Generally the density of the coal from the primary cells will contain about 35% solids and thus does not require thickening ahead of filtration.
Coal from the coarse flotation and the gravity section, if employed, can be readily dewatered over screens or horizontal or top feed filters. In some cases it may be possible to divert part or all of this coal to the filter handling the fines provided it is equipped with proper agitation equipment and a high displacement vacuum system. Some of the new synthetic filter bag fabrics such as Saran and nylon materially aid in securing high filter rates and low final moisture content.
Sub-A Coal Flotation Systems have been successful for recovery of both coarse and fine coal. It is important, however, to employ a two-stage circuit for maximum efficiency in saving the plus 28 mesh fraction which is normally the most difficult to float. The development of the free flow and Type M flotation cells offers a means for efficiently handling coarse coal in a size range heretofore reserved for other more complex systems.
Ash and sulphur content is desired to be as low as, or lower than, for regular lump coal. Generally, for anthracite, not over 13 per cent ash is desired. Bituminous coal operations usually limit ash to not more than 8 per cent in the fines.
Flotation or gravity concentration are generally applied only to washery fines that otherwise would not be saleable and which generally have to be impounded to prevent stream pollution. Because of the low price secured, the expense of treatment must be held to a minimum. Pyrite and coarser ash-forming content may need to be removed by gravity treatment.
Kerosene or fuel oil with pine oil, or alcohol, frother are the more common reagents used. Cresylic acid frother may sometimes be advantageous. Fine pyrite, if free, may be rejected with the high-ash refuse by addition of lime to the flotation feed.
Under proper conditions, coal as coarse as 10 mesh maybe effectively floated with kerosene and pine oil. For this coarse flotation it is generally necessary to classify out the high-ash 200 mesh slimes ahead of flotation.
A gold beneficiation process, the process uses two and a half of a closed-circuit crushing, two stage two closed-circuit grinding and flotation and then by selection, selection of its tailings swept away by a rough sorting operations, will be selected tailings and sweep the election together combined ore concentrate regrinding, the high efficiency of this process broken, broken fine-level content and the final product was 81.55%, high crushing capacity, processing capacity per hour is 53. 84 tons, working time is short, and the sorting effect, high-technology index, and the concentrate grade and recovery rates can improve synchronization, high recovery rate targets, increased 3.03%, concentrate grade increased 16.57g / t, power consumption reduced by 21.5%, 18.9% reduction in the cost, the annual cost increase of 8.6012 million yuan. Throughout the centuries, gold has been recovered from its ores in many ways. These range from the rocker or long tom of the California Forty-Niner and the noisy stamp mill of the 19th century to modern methods of leaching with cyanide. Any method of treating gold ores must take advantage of the natural characteristics of the metal. Cyanide solution, unlike most other liquids, is able to dissolve gold, and thus, is used in the processing of gold ore. When in solution (and in the presence of oxygen), cyanide slowly attacks fine particles of gold and ultimately dissolves them. It is strange, but fortunate (because cyanide is extremely toxic), that a weak cyanide solution attacks the gold particles faster than a strong solutions.
For the cyanide to attack the gold particles, it is necessary that the gold first be liberated from the worthless gangue rock which surrounds it because cyanide will not attack or dissolve most other minerals. Overall, the cyanide process is very efficient. A gold ore containing less than one gram of gold per ton can, in some cases (and depending on the gold price), be profitably treated. A modern cyanide mill recovers or extracts 95% to 98% of the gold in the ore. In a cyanide mill, lime and cyanide are added to the ore pulp in the grinding circuit. The lime has several functions: it protects the cyanide from being destroyed by naturally occurring chemicals called cyanicides and improves the settlement rate of the pulp in the thickening stage. Cyanidation (the actual dissolution of the gold) begins in the grinding step. Cyanide and lime solutions are introduced here, where newly liberated gold particles are constantly being polished by the grinding action and the solutions are heated by the friction. Depending on the ore and fineness of grind, from 30% to 70% of the gold may be dissolved during the grinding process. Additional time is required to place the balance of the liberated gold into solution. This is done by pumping the gold-bearing pulp to a number of mixing tanks, known as agitators.
Here the pulp is aerated either mechanically or by compressed air, or by a combination of both, for a predetermined period of time. This varies any where from 24 to 48 hours. The 1980s saw a rapid expansion in gold production from low-grade oxide deposits around the world. That expansion could not have occurred without the development of a new, low-cost method of recovering the gold. That process is called heap leaching. Heap leaching avoids most of the above steps, and does not even require that a mill be built, making it a very low-cost method of processing ore. Here, broken ore is heaped onto a thick polyethylene sheet, called a liner, and then dilute cyanide solution is sprinkled on top of the heap. As the solution trickles down through the ore, the gold is dissolved. Before the heap is constructed, the polyethylene liner is laid down in such a way that the cyanide solution will drain to a central point. From here the gold-laden solution is channeled into a man-made pond. One downside of heap leaching is lower recovery just 65% to 85% of the gold in the ore ends up in the gold bars a heap-leach mine produces. Extracting Gold Out of Solution: Traditionally, recovering the gold from the cyanide solution was achieved by separating the gold-laden, or pregnant, solution from the barren solids present and then precipitating the gold. The traditional approach is called the Merrill-Crowe method. The first step is to move the pulp from the agitators to one or more thickeners large, shallow tanks. The solution flows over the top of the tank and is collected in a launder around the tanks perimeter, while the worthless rock particle sink to the bottom and are slowly raked to the center by mechanical arms which operate continuously. The material is discharged through a pipe at the bottom of the tank but it contains too much valuable material to be discarded, so is filtered to recover additional gold.
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The beneficiation of magnesite is based on heavy medium and thermal separation methods. With the advancement of science and technology and the improvement of the quality requirements of concentrates, flotation and chemical beneficiation have become important means of magnesite purification.
Flotation is one of the main methods for processing magnesite. For gangue minerals such as talc, quartz and other ores dominated by silicate minerals, the flotation process is usually performed under the natural PH of the pulp, and an amine cationic collector is added. And foaming agent can achieve good results, increasing the purity of magnesite to 95%-97%.
Crushing and screening: the raw ore with a particle size of less than 200mm is crushed to 10~0mm by a jaw crusher, a pair of roller crusher and a vibrating screen in a two-stage closed-circuit process, and used as a ball mill to feed the ore;
Flotation: the flotation process consists of reverse flotation (one coarse and one sweep) and positive flotation (one coarse and one sweep) The former selects all tailings, and the latter obtains magnesia concentrate and medium ore.
Light burnt: Calcined magnesite at 750~1100 temperature is called "light burnt", and its product is called light burnt magnesia powder. Since the burning loss of magnesite is generally about 50%, the content of MgO in the ore can be almost doubled through light burning. In this sense, light burning is the most effective MgO enrichment method. In addition, light burning is also a preparatory operation for magnesite thermal separation and certain heavy separation. Light burned magnesia has high activity and is an ideal raw material for the production of high-density magnesia.
Thermal separation method: use the difference in thermal properties between magnesite and talc to cause the difference in density and hardness between the two after calcination, and then separate the minerals through selective crushing and simple screening or classification. The flotation process is simple and low in cost.
In addition to the above-mentioned flotation method, light burning method, and thermal separation method, magnesite ore beneficiation also includes gravity separation method, electric separation method, radiation separation method, magnetic separation method, and so on.
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