magnetic separation method with diagram

magnetic separation method

Magnetic separation is a process used to separate materials from those that are less or nonmagnetic. All materials have a response when placed in a magnetic field, although with most, the effect is too slight to be detected. The few materials that are strongly affected (magnetised) by magnetic fields are known as Ferromagnetics, those lesser (though noticeably) affected are known as Paramagnetics.

Ferromagnetics require relatively weak magnetic fields to be attracted and devices to separate these materials usually have magnets that are permanently magnetised (Permanent magnets do not require electricity to maintain their magnetic fields). Paramagnetics require stronger magnetic fields and these can only be achieved and maintained by electro magnets (large wire coils around an iron frame current is continuously passed through the coils creating the magnetic field within the iron. The field is concentrated across an air gap in the circuit).

Both ferromagnetic (low intensity) and paramagnetic (high intensity) separation devices (Laboratory Magnetic Separator) may be operated with dry solids or with solids in pulp form. (A complete classification of magnetic separating devices is given in Wills Mineral Processing Technology, pp. 338-356).

(*The units given are kilogauss (kG). These are the units most commonly used. The equivalent S.I. unit is the Tesla (T) * 1 Tesla = 10 kilogauss). The extremes of field strength used are based on experience from a magnetic separation testing laboratory over many years.

magnetic separation - an overview | sciencedirect topics

Magnetic separation takes advantage of the fact that magnetite is strongly magnetic (ferromagnetic), hematite is weakly magnetic (paramagnetic), and most gangue minerals are not magnetic (diamagnetic).

The current research and development initiatives and needs in magnetic separation, shown in Fig. 7, reveal several important trends. Magnetic separation techniques that have been, to a greater extent, conceived empirically and applied in practice, such as superconducting separation, small-particle eddy-current separation, and biomedical separation, are being studied from a more fundamental point of view and further progress can be expected in the near future.

In addition, methods such as OGMS, ferrohydrostatic separation, magnetic tagging, and magnetic flocculation of weakly magnetic materials, that have received a great deal of attention on academic level, are likely to enter the development and technology transfer stages.

The application of high-Tc superconductivity to magnetic separation, and novel magnetism-based techniques, are also being explored, either theoretically or empirically. It can be expected that these methods, such as magnetic flotation, magnetic gravity separation, magnetic comminution, and classification will take advantage of having a much wider control over these processes as a result of the presence of this additional external force.

Magnetic separation takes advantage of the fact that magnetite is strongly magnetic (ferromagnetic), hematite is weakly magnetic (paramagnetic), and most gangue minerals are not magnetic (diamagnetic). A simple magnetic separation circuit can be seen in Figure 1.2.5 [9]. A slurry passes by a magnetized drum; the magnetic material sticks to the drum, while the nonmagnetic slurry keeps flowing. A second pass by a more strongly magnetized drum could be used to separate the paramagnetic particles from the gangue.

Magnetic separation can significantly shorten the purification process by quick retrieval of affinity beads at each step (e.g., binding, wash, and elution), and reduce sample dilution usually associated with traditional column-based elution. The method can be used on viscous materials that will otherwise clog traditional columns and can therefore simplify the purification process by eliminating sample pretreatment, such as centrifugation or filtration to remove insoluble materials and particulates. The capability of miniaturization and parallel screening of multiple conditions, such as growth conditions for optimal protein expression and buffer conditions for purification, makes magnetic separation amenable to high-throughput analysis which can significantly shorten the purification process (Saiyed et al., 2003).

Paramagnetic particles are available as unmodified, modified with common affinity ligands (e.g., streptavidin, GSH, Protein A, etc.), and conjugated particles with specific recognition groups such as monoclonal and polyclonal antibodies (Koneracka et al., 2006). In addition to target protein purification, they can also be used to immobilize a target protein which then acts as a bait to pull down its interaction partner(s) from a complex biological mixture. See Chapter 16.

Magnetic separation of cells is a simple, rapid, specific and relatively inexpensive procedure, which enables the target cells to be isolated directly from crude samples containing a large amount of nontarget cells or cell fragments. Many ready-to-use products are available and the basic equipment for standard work is relatively inexpensive. The separation process can be relatively easily scaled up and thus large amount of cells can be isolated. New processes for detachment of larger magnetic particles from isolated cells enable use of free cells for in vivo applications. Modern instrumentation is available on the market, enabling all the process to run automatically. Such devices represent a flexible platform for future applications in cell separation.

IMS play a dominant role at present but other specific affinity ligands such as lectins, carbohydrates or antigens will probably be used more often in the near future. There are also many possibilities to combine the process of cell magnetic separation with other techniques, such as PCR, enabling the elimination of compounds possibly inhibiting DNA polymerase. New applications can be expected, especially in microbiology (isolation and detection of microbial pathogens) and parasitology (isolation and detection of protozoan parasites). No doubt many new processes and applications in other fields of biosciences and biotechnologies will be developed in the near future.

Magnetic separation methods are widely used for isolation of a variety of cell types. Magnetic particles with immobilized antibodies to various antigens have been employed for the rapid isolation of populations T-(CD4 +, CD3 +, CD8+) and B- (CD19+) of lymphocytes, NK cells, and monocytes. Similarly, immobilization of glycoconjugates on magnetic beads allows the isolation of cell populations expressing a particular carbohydrate-recognizing molecule [19, 20]. Glycosylated magnetic beads can be prepared by loading biotinylated probes onto streptavidin-coated magnetic beads. The glycoparticles are then incubated with a cell suspension and the subpopulation of interest is fished out by means of a magnetic device [20].

When these materials are used in the biological field, special restrictions should be considered and all possible reactions with the biological materials should be predicted. Magnetic properties should be maintained for a specific time during the test. Some applications can be classified as follows:

Magnetic separation is used for clinical application, such as in the separation of proteins, toxemic materials, DNA, and bacteria and viruses. This is also used for real time detecting of viruses. The most important stage in this field is the labeling of molecules with magnetic materials by a reliable connection. Magnetic beads from iron oxide are typically used for biological separation. The main properties of iron oxide are super paramagnetic properties (Meza, 1997).

Effective drug delivery can greatly improve the process of treatment and reduce side effects. In this method, while the amount of drug decreases, the concentration of the drug in the target area increases. Protecting the drug before its gets to the target area is one of the most important factors, because after releasing the drug in the blood stream, white cells detect the drug and swallow them in a short time. An ideal nanoparticle for drug delivery should have the potential to combine with a relatively high-weight drug and disperse uniformly in the blood stream (Shultz et al., 2007).

Also, while chemotherapy is one of most effective methods for cancerous tissues, many of the other healthy cells are destroyed in the process. So the conventional thermotherapy has many side effects. In hyperthermia treatment, after delivering the drug to the target area, an AC magnetic field is used to generate controllable energy and increase temperature. Heat transfer in this process is a balance between blood flow, heat generation, and tissue porosity and conductivity (Sellmyer and Skomski, 2006).

Magnetic Resonance Imaging (MRI) is considered a great help in the diagnoses of many diseases. The advantages of this imaging are high contrast in soft tissue, proper resolution, and sufficient penetration depth for noninvasive diagnosis. In fact, in MRI imaging magnetization of protons is measured when exposed to the magnetic field with radio frequency (Corot, 2006).

Magnetic separation: based on the generation of magnetic forces on the particles to be separated, which are higher than opposing forces such as gravity or centrifugal forces. This principle is used to separate ferromagnetic particles from crushed scrap mixtures.

Eddy current separation: is a particular form of magnetic separation. An alternating magnetic field induces electrical eddy currents on a metal particle. This results in a magnetic field whose direction is opposite to the primary magnetic field. The exchange interactions between the magnetic fields result in a repulsive force on the metallic particle; the net effect is a forward thrust as well as a torque. This force and hence the efficiency of separation is a function of the magnetic flux, or indirectly of the electrical conductivity and density and the size and shape of the metallic particles.

Air separation/zigzag windsifter: Air-based sorting technique, which separates the light materials from the heavier. The most prominent application is in shredder plants producing the shredder light fraction, or in fridge recycling, removing among others the polyurethane (PUR) foam from the shredded scrap.

Screening: Separation of the scrap into different particle size classes is performed to improve the efficiency of the subsequent sorting processes and/or to apply different processing routes for different size fractions (based on material breakage and hence distribution over various size fractions).

Fluidized bed separation: A fluidized bed of dry sand is used to separate materials based on density. This technology is in principle a dry sink-float separation, which is still hampered by several difficulties (tubular or hollow particles filling up with sand and tend to sink; formation of unsteady current due to the use of high velocity air, etc.). The fluidized bed could also be heated for simultaneous de-coating and combustion of organic material.

Image processing (including colour sorting): Colour sorting technologies, which sense the colour of each particle and use computer control to mechanically divert particles of identical colour out of the product stream (red copper, yellow brass, etc.). A complicating issue is that shredding results in mixtures of particles that show a distribution in composition, size, shape, texture, types of inserts, coatings, etc. The variance of these properties complicates identification that is solely based on this principle.

X-ray sorting: Dual energy X-ray transmission imaging (well known for luggage safety inspections at airports) identifies particles based on the average atomic number, particle shape, internal structure (e.g. characteristic variations of thickness) and presence of characteristic insert material. It is rather sensitive to particle thickness and surface contaminations.

LIBS (laser induced breakdown spectroscopy) sorting: A series of focused ablation laser pulses are delivered to the same spot on each particle. A pulse of an ablation laser vaporizes only the first nanometres of the surface, i.e. the first pulses are necessary to clean the surface of oxide layers (different composition than the mother metal), the last pulse vaporizes a tiny amount of metal generating a highly luminescent plasma plume. The light from the plasma is collected and analysed to quantitatively determine the chemical composition. This determines to which bin the particle is directed (e.g. by air pulse).

Iron ore processors may also employ magnetic separation for beneficiation of classifier output streams. Wet high-intensity magnetic separators (WHIMS) may be used to extract high-grade fine particles from gangue, due to the greater attraction of the former to the applied magnetic field.

In addition to beneficiating the intermediate middlings streams from the classifier, WHIMS may be used as scavenger units for classifier overflow. This enables particles of sufficient grade to be recovered that would otherwise be sacrificed to tails.

Testwork has been performed on iron ore samples from various locations to validate the use of magnetic separation following classification (Horn and Wellsted, 2011). A key example was material sourced from the Orissa state in northeastern India, with a summary of results shown in Table 10.2. The allmineral allflux and gaustec units were used to provided classification and magnetic separation, respectively.

The starting grade of the sample was a low 42% Fe. It also contained significant ultrafines with 58% passing 20m. This is reflected in the low yield of allflux coarse concentrate; however, a notable 16% (abs) increase in iron grade was eventually achieved. The gaustec results for the middlings and overflow streams demonstrate the ability to recover additional high-grade material. With the three concentrate streams combined, an impressive yield of almost 64% was achieved with minimal decline in iron grade.

The automatic separation system, developed by Magnetic Separation System of Nashville, Tennessee, uses X-ray, IR, and visible spectra sensors for separating the post-consumer recyclate bottles or flakes into individual plastics and into different color groups. X-ray sensors, used for separating PVC, are very accurate and can operate at as high as 99% or better efficiency. IR and visible sensors are used to separate the colored bottles into individual polymers and color groups.

The separation system (Figure 4) essentially consists of a metering inclined conveyer, air knife, special disk screen, singulating infeed conveyor, and sensor module. A motor control system provides operator interface screens which control the sorting functions, including the number of bottles sorted into each fraction, ejection timing, and sort positions. Individual systems currently in use in Germany, Switzerland, and the United States are described in a paper by Kenny and Vaughan.16 The systems are customized, based on the composition of the post-consumer recyclate and the end application of the separated streams. Some systems use X-ray and IR sensors in two locations to achieve better separation. In addition to sorting equipment, some systems also use equipment for breaking the bales and splitting the bottles into more than one stream for smooth operation. Grinders are used when the bottles have to be ground into flakes for further processing. Whereas PVC separation is accomplished at 99%. HDPE and PET separation is between 80 and 90%, depending on the level of contamination.

Automated separation provides two advantages: improved quality and lower labor cost for sorting. The automatic separation system at Eaglebrook Plastics uses the Magnetic Separation System (MSS), which detects and separates the bottles into different categories based on the type of the resin and color, and eliminates impurities such as broken pieces of plastics, rocks, aluminum cans, and other contaminants.17 Metering the feed is critical to obtain maximum throughput at Eaglebrook. This is accomplished by a special debaling device and an incline metering system. Factors contributing to proper operation include clear height, width, spacing, belt speed, and incline angle. Proper presentation of the bottle to the sensor is critical. The bottles are split into four streams and two to three bottles are presented to the sensor per second, one at a time.

The primary identification sensor uses a multibeam, near-IR array to identify the bottles into three classes: Class 1, PVC, PET; Class 2, natural HDPE, PP; Class 3, mixed color HDPE and opaque containers. This sensor is also capable of separating colored PET from clear PET and PP from milk jug HDPE. The X-ray sensor identifies PVC, and a machine vision sensor system provides up to seven color classifications of the plastic bottles. After identification, the containers are ejected from the conveyors into appropriate collection stations using high-speed pulsed air nozzles. The motor control center (MCC) of the separation system controls motor protection, sequential slant up for the system, fault indication, and operation control. In addiiton, a touch screen input panel allows the operator to select any available sort to be directed to any ejection station. Visible light color sensors have been added which sort pigmented HDPE into different colors. The system also includes a decision cross-checking device between the primary sensor and the color sensor. This compares the decisions of the two sensors by comparing them with a logic file. The latter then provides correct identification in case there are discrepancies between the two decisions. The system has successfully operated for the last three to four years at a capacity of 5000 bottles h1.

The debaling system designed for Eaglebrook requires that the bales be presented to the debaling equipment in the same orientation as the original compression. This design feature requires less horsepower, reduces bottle clusters, and requires minimum energy. The debaling and declumping system incorporates a surge bin and metering conveyor to feed the screening system. The improved capacity and higher separation accuracy, due to increased metering efficiency, reduces bottle clusters and provides a more uniform feeding system. The separation efficiency depends on several factors. Timing and catcher bounceback accounts for 12% accuracy loss; contamination, container distortion, and loose labels contribute to about 34%, and nonsingulation of the bottles 510% of accuracy loss.

Asoma Instrument of Austin, TX, is a leading manufacturer of automated bottle sorting equipment. The company uses an X-ray fluorescence spectrophotometer sensor. The identification is completed in 10ms and the separation takes about 20s per bottle. The sorted PET streams have less than 50ppm PVC. National Recovery Technology of Nashville, TN, uses a proprietary electromagnetic screening process which can handle the bottles either in crushed or whole form and does not require any special positioning or orientation of the bottle to achieve high efficiency. Chamberlain/MCR, Hunt Valley, MD, and Automation Industrial Control of Baltimore, MD, offer a paysort bottle sorting system, which uses a sophisticated video camera and color monitor incorporating a strobe to detect and distinguish colors of post-consumer bottles following a near-IR detection system which also determines the primary resin found in each bottle.

A substantial amount of research is focused on microseparation techniques and on techniques which can reject bottles with trace amounts of harmful contaminant. Near-IR spectrometry is being used to separate bottles for household chemicals and ones with hazardous waste residues.

Sorting of automotive plastics is more difficult than sorting of plastics from packaging recyclates. Whereas only five to six polymers are used for packaging, post-consumer automotive plastics contain large numbers of engineering and commodity plastics, modified in various ways, including alloying and blending, filling, reinforcing, and foaming. Hence, sorting of automotive plastic recyclate poses several challenges. Recently, a systematic study, PRAVDA, was undertaken by a German car manufacturer and the plastic suppliers in Europe to investigate the potential of various analytical techniques in separating post-consumer automotive plastics.18

The techniques examined in this study include near-IR spectroscopy (NIR), middle-IR spectroscopy (MIR), Fourier transform Raman spectroscopy (FTR), pyrolysis mass spectrometry (PY-MS), pyrolysis IR spectroscopy (PYIR), and laser-induced emission spectral analysis (LIESA). X-ray methods were excluded because they have insufficient sensivitity to polymers, other than ones containing chlorine. Since commercial spectrophotometers were not available for most techniques except NIR, either laboratory models (MIR, FTR) or experimental stage instruments (PY-MS, PY-IR, and LIESA) were used in this study. A large number of parts (approximately 7000) were analyzed. The techniques were compared in respect to their success in identification, fault rate, time for identification, degree of penetration, and sensitivity to surface quality. The fault rate is the number of wrong identifications, given as percent. If the sum of the identification and fault rate is less than 100, the difference gives the rate of incomplete correct identification. The biggest stumbling block was the identification of black samples which could not be analyzed by NIR and FTR. MIR is the only technique which not only identified the black samples, but gave the highest identification rate. Some difficulties were experienced, however, in MIR analysis in the case of blends of two similar polymers such as PP/EPDM or nylon 6/nylon 66. The pyrolytic methods showed poorer identification rates and higher fault rates. The LIESA method is very fast and a remote technology, particularly for fast identification of heteroatoms. It is therefore suitable for identifying fillers, minerals, reinforcing fibers, pigments, flame retardants, and stabilizers specific to the individual plastic. The difficulty with MIR is that it is sensitive to surface micro-roughness and, hence, the samples need to be very smooth. Also, paint or surface coats on the part have to be removed for correct identification of the resin used for making the parts. Further, at this stage, no fiber optic or separated probe is available with MIR technology and, hence, the part has to be brought close to the spectrophotometer instead of the probe reaching the part. Another method of measuring efficiency is the level of contamination. Contamination of parts sorted by the MIR method was less than 1%, whereas contamination of parts sorted manually, using a Car Parts Dismantling Manual, is greater than 1015%. When the level of contamination is high, further separation by swim-sink or hydrocyclone techniques are necessary.

The cost of a MIR spectrophotometer is approximately DM 100000. The cost calculated for small dismantlers (dismantling less than 25 cars per day) is approximately DM 0.34 per kg and that for large dismantlers is somewhat less than DM 0.19. Manual sorting, on the other hand, would cost DM0.71 and DM0.23 per kg for small and large dismantlers, respectively. Spectrophotometric identification of plastics in automotive plastics waste therefore makes substantial economic sense.

what is magnetic separation? (with pictures)

Magnetic separation is an industrial process where ferromagnetic contaminants are recovered from materials on the production line. Manufacturers use this to extract useful metal, separate recycling, purify materials, and perform a wide variety of other tasks. Manufacturers of magnetic separation equipment may have a range of products available for sale for different applications, including an assortment of sizes with strong and weak magnetic fields to attract different kinds of magnetic material.

The magnetic separator consists of a large rotating drum that creates a magnetic field. Materials enter the separator and fall out through mesh at the base if they are not magnetic. Sensitive particles respond to the magnetism and cling to the sides of the container. The drums can be used in continuous processing of materials as they move along the assembly line, or in batch jobs, where a single batch is run through all at once.

One common use for magnetic separation is to remove unwanted metal from a shipment of goods. Magnetic separation can help companies keep materials pure, as well as remove things like nails and staples that may have crept into a shipment. The equipment can also purify ores, separate components for recycling, and perform a variety of other tasks where metals need to be separated or isolated. Equipment can range in size from a desktop unit for a lab that needs to process small amounts of material to huge drums used in scrap metal recycling centers.

Manufacturers of magnetic separation equipment typically provide specifications for their products for the benefit of prospective customers. Consumers may need equipment that targets a specific range of metals, or could require large size or high speed capacity. It may be possible to rent or lease equipment for some applications, or if a factory wants to try a device before committing to a purchase. Used equipment is also available.

A gentler form of magnetic separation can be used for delicate tasks like removing magnetic materials from cremated remains or finds at an archaeological site. In these situations, a technician carefully moves a magnet over the material to pull out materials like staples and jewelry. At a crematorium, this is necessary before ashes are ground, as metal objects can damage the equipment. For archaeologists, it can provide a mechanism for carefully separating materials at a find and documenting the position and location of various objects as the archaeologist uncovers them on site or in a lab.

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.

@allenJo - I do believe they use these systems in water treatment systems. I dont know the mechanisms used but it is used from what Ive heard. Water should give up its magnetic particles quite easily, I would think, since the metals are just floating about like flotsam and jetsam in the ocean.

@Charred - Those are two very good points, and I am sure that they are accounted for. The uses described in the article suggest scenarios where the metals are rather loosely fitting, so I think the cleanup job would be thorough. What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

What I wonder about is if this process can be adapted to water treatment? Since magnetic separation systems can be used to sift through fluids, could they purify water as well? That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

That seems to be an obvious application. Where I live the tap water has a lot of metals and so we generally dont drink it. I already have three metal fillings; I dont need more metal in my body.

I see two things here that are necessary for magnetic separation to work well. First, the metals must be easily dislodged from whatever material or goop they happen to be sitting in. Otherwise, theyll just remain stuck, and the separation will be less than effective in pulling out all the metals. Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

Second, the magnetic drum separator itself must be sufficiently strong. I think thats obvious, and the second point is related to the first. If the separating device is not strong it wont dislodge the metals; but there may be situations where the device is strong, but the metals are just stuck and wont budge.

magnetic separation 42 bio

Biotech applications, ever more frequently, are requiring the isolation of biological components from complex mixtures. Current technologies to recover cells and biomolecules from blood and plasma are slow, inefficient and only work on small volumes. Via rational design of high-gradient magnet arrays combined with planar flow separation chambers, 42Bio has developed a faster, more scalable and more efficient technology for isolating various cell types and biomolecules from complex biological fluids. Magnetic particles bound to stem cells and biomolecules respond rapidly to our proprietary magnet arrays, facilitating highly efficient separation from larger volumes over very short time periods.

In the lab setting, components are routinely separated from mixtures using magnetic separation techniques. 42Bio's magnetic separation technology method works equally well for large components like whole cells, to small components like single molecules or peptides.

Current magnetic separation technologies either employ a magnet attached to the side of a small tube, or a small tube with a magnetizable mesh inside. In the latter case, when a magnetic field is applied, the mesh becomes magnetized, trapping the particle/target components. However, there are significant limitations to both of these approaches. These techniques work well for small separation volumes but there are significant limitations when voulumes or flow rates are increased. The rapid drop in magnetic field strength and gradient with distance from the magnet means that using tubes with larger diameters does not generate enough force on particle/target complexes flowing through the middle of the tube. Stronger/larger magnets work to a degree, but the exponential decay of the field limits eve this approach. In the case of magnetizable mesh systems, a second issue is clogging. As more particle/target complexes are trapped in the mesh, flow becomes blocked, significantly limiting the processing volumes.

Using a rational engineering approach 42Bio has solved these challenges. Instead of relying on increasing the size of the magnet, we have developed novel magnet array geometries that distribute high magnetic fields and gradients over a planar surface, enabling easy scale-up to large fluid volumes and flow rates under planar flow conditions. Our patented device for the separation of magnetic particles spreads the volume out into a thin sheet where the penetration of the magnetic fields is significantly enhanced. That is to say that there is more magnetic field/gradient density per unit volume in our geometry. This enables easy scalability while maintaining high target separation efficiency. While the components of this approach seem relatively straight forward, it is the integration and balance of all of these aspects that is the key to 42Bio's new technology.

42Bios mission is to develop and implement regenerative medicine technologies to advance human and veterinary health. We are committed to seeking answers to some of the biggest questions in the field of life sciences.

diagram of the isodynamic magnetic separator binq mining

21 Jul 1993 isodynamic region against increasing magnetic force. . the magnetic circuit of the separator and the scales engraved on the chute carriage Vihrator control unit: A circuit diagram for the control unit for the feed and chute

the principles of gravity separation and magnetic separation. Separation of heavy -mineral . slope 20, tilt 25] on the Frantz Isodynamic Magnetic Separator. Table 5-2 Diagram your estimates of the percentages of various particletypes on

Mineral separation for geochronology is a time consuming job. . in pictures and a flow diagram, which have been successful used since 30 years (magnetic separator) can be used in other institutions. . The FRANTZ isodynamic magnetic

The magnetic field in the working space of the separator with no current The diagram on the right shows a stabilized minor hysteresis loop for the magnetic circuit which serves the Isodynamic and the Magnetic Barrier Laboratory Separators.

18 Dec 1991 Abstract Selectivity is a severe problem in dry magnetic separation. Dry rotating- disk anadynamic or isodynamic magnetic fields are .. grade-recovery diagram is shown in Figure 9. lOT/m. grodiB!

AB S T R ACT: Two types of cells for magnetic separation of clay minerals in aqueous suspension, were designed. The ceils can be used with a standard Franz Isodynamic. Separator. Perspective diagram of cell No. 1 to be used with a

The rocks were crushed and sieved, the grain sizes used for separation a hand magnet and an isodynamic magnetic separator used to remove .. Tsueor, S. ( 1934) A straight-line diagram for determining plagioclases by the dispersion

Applications of magnetic cell separation include detection of rare cancer cells in A specialized method based on a nearly isodynamic magnetic field Schematic diagram of cell tracking velocimeter and the region of interest where the

Wet magnetic separation of the crude ilmenite concentrate at 2000-3000 .. As the type of magnetic separator to be used in this study is a Frantz isodynamic separator, .. Figure is a ternary phase diagram of these oxides and their solid

An isodynamic chart for the Earth's magnetic field is shown to the left. or a small diagram showing the relationship between magnetic north and true north. .. This buoyancy is enhanced by chemical separation: As the core cools, some of the

what is concentration of ore? definition, physical & chemical methods - biology reader

To obtain a pure metal from ore, the method of ore concentration is a very crucial step. For the extraction of metal, it is necessary to separate ore from the gangue particles. Ore found in the earth contains many impurities like sand, grit, rocks etc. which are collectedly known as Gangue.

The concentration of ore is the first step of metal extraction. There are different types of ore like native, oxidized, sulphurized and halide, which can be concentrated by various physical and chemical methods.

The ore concentration is defined as the chemical process of eliminating impurities like sand, rocks, silt, grit etc. from the ore to extract the metals. In simple words, the concentration of ore is the method of separating ore from the gangue, as the gangue or matrix particles are the valueless substances that are of no use. The ore can be concentrated or separated by both physical and chemical means. The ore obtained after the completion of the ore concentration is called concentrate.

Ore can define as a solid substance (like a rock) that contains minerals or combination of minerals, from which the metal can be extracted by a series of methods like the concentration of ore, isolation of metal and refining of the metal.

As the ore is found in the earths ground surface, it contains unwanted earthy materials like rocks, sand, silt, and many other impurities colloquially termed as gangue. The concentration is basically the separation of something useful out of worthless. Thus, by concentrating ore from such impurities, we can actually extract and refine metals. Various physical and chemical processes are employed to concentrate or separate ore from the gangue matrix.

It was the traditional method of concentrating ore directly with hands. In this method, the gangue or adhering solid matrix is separated from the ore with a hammers help. The separation and identification of gangue are made based on the differences in colour or lump shape.

It is also called Gravity separation or Levigation. In the hydraulic wash, the ore is separated from the gangue by the principle of gravitational force. The ore is first crushed into fine particles or powdered form. Then, the powdered ore is passed through the water current. As the ore is more substantial than the gangue particles, it will settle behind, and the gangue will float away through the stream of water. The process of hydraulic washing is accomplished by Hydraulic classifier or Wilfley table. This method is widely used for the concentration of oxide and carbonate ores.

The magnetic separation method separates ore from the gangue particles based on the magnetic properties of either ore or matrix. In this method, the ore is finely crushed and passed over the magnetic roller, where one is magnetic, and the other is nonmagnetic. The magnetic ore particles will attract and attach to the magnetic roller, and the non-magnetic gangue particles will repel and fall into the heap from the conveyer belt. Example: Fe (CrO2)2 (Chromite) is a magnetic ore, separated from the non-magnetic silicious gangue.

In this process, finely ground ore or we can say pulp of ore is passed into the bioreactor along with little oil. The oil which is generally used in the froth floatation process is pine oil. The bioreactor contains water onto which the mixture of ore plus oil is added through an inlet. Then, the mixture of ore, oil and water is thoroughly mixed or agitated by the rotating paddle (comprises impellers) that allows uniform mixing of all the components. There is constant airflow inside the medium, which leads to the formation of mineral froth (appears as a supernatant). Froth contains mineral particles that can be collected by transferring the mineral froth into the other bath, in which the ore free from gangue will settle down.

part 3: different methods of sorting & preparing waste | waste management

There are many different ways that waste recovery facilities sort and prepare waste. On this scale, machinery is often used to make the process more efficient. Waste sorting municipal waste often starts manually at the household.

It is important that waste is sorted before it moves onto the next process of treatment or disposal. This will determine the preferred disposal method suited to the waste stream is chosen, resulting in less waste ending up in landfills.

Bulky items such as large pieces of wood, rocks, long pieces of cloth, etc. are removed by hand before mechanical processing begins. Equipment involved in manual separation usually includes a sorting belt or table. Hand picking of refuse is perhaps the most prevalent MSW handling technique; it is also the only technique for removal of PVC plastics.

Hand separation is time consuming and labour intensive however, it does allow for the sorting of waste in a manner which contributes towards having better separation of waste and the recovery of recyclable materials.

In this method, fans are used to create a column of air moving upwards. Low-density materials are blown upwards, and dense materials fall. The air carrying light materials, like paper and plastic bags, enters a separator where these items fall out of the air stream. The quality of air separation depends on the strength of the air currents and how materials are introduced into the column. Moisture content is also critical as water may weigh down some materials or cause them to stick together.

There are two types of devices are commonly used for this process: hammer mills and shear shredders. Hammer mills consist of rotating sets of swinging steel hammers through which the waste is passed, and shear shredders are used for materials that are difficult to break apart such as tires, mattresses, plastics, etc. The hammers need frequent resurfacing or replacement. Both are energy and maintenance intensive. Hammer mills shatter items such as fluorescent light bulbs, compact fluorescent lamps, and batteries.

Another methodology for reducing the waste size is to place the waste into a centrifugal shredded system which reduces the original volume by 80% and the weight by 50%. This allows the physical particle size to be reduced, but more importantly reduce the moisture content of the waste.

A trommel screen, also known as a rotary screen, is a mechanical screening machine used to separate materials, mostly solid-waste processing industries. It consists of a perforated cylindrical drum that is normally elevated at an angle at the feed end. For an inclined drum, objects are being lifted and then dropped with the help of lifter bars to move it further down the drum; otherwise, the objects roll down slower. Furthermore, the lifter bars shake the objects to segregate them. Lifter bars will not be considered in the presence of heavy objects as they may break the screen.

Physical size separation is achieved as the feed material spirals down the rotating drum, where the undersized material smaller than the screen apertures passes through the screen, while the oversized material exits at the other end of the drum. In municipal solid waste industry, trommel screens classify sizes of solid waste. By removing inorganic materials such as moisture and ash from the air-classified light fraction segregated from shredded solid waste, trommel screening improves the fuel- derived solid waste.

Drying process reduces the moisture content of waste and prevents the leachate production- which could seep into the water if the waste were disposed of in land fill or stored in an open area over long periods of time.

Dried materials tend to be inactive biologically and are easier to store. This results in a homogeneous refuse-derived fuel (RDF). Any partially decayed waste should be dried either under the sun, by hot air, or by a combination of both if applicable.

Although the option to air dry in the UK is very limited for customer/ clients, for those who operate in different parts of the world, this could be considered as part of the initial feasibility study.

This important step in the process differs in each facility depending on the investment or land availability. Solar drying is not possible during rainy seasons and most facilities run at a fraction of their capacity during the rainy season, sending most of the waste to landfills. Mechanical drying, on the other hand, requires significant amounts of energy that could easily render RDF plants unprofitable without huge government subsidies.

Electro-magnets are used in this step so they can be switched on or off to allow removal of collected metals. However, not all metals can be removed by magnets. Non-ferrous metals do not have iron and do not respond to the magnetic field.

Stainless steel, copper, and aluminium, for example, are only weakly magnetic or are not magnetic at all. A further limitation of this technique is that small magnetic item will not be picked up if they are buried in non-magnetic materials and larger magnetic items can drag unwanted items like paper, plastic, and food waste along with them.

The image demonstrates a separation of non-ferrous metals from inert materials in an eddy current separator. Eddy current separators, or non-ferrous separators, use the current induced in little swirls (eddies) on a large conductor and separate non-magnetic metals.

An eddy current is a swirling current set up in a conductor in response to a changing magnetic field. If a large conductive metal plate is moved through a magnetic field which intersects perpendicularly to the sheet, the magnetic field will induce small rings of current which will actually create internal magnetic fields opposing the change.

Eddy current separators handle high capacities because the conveyor belt separates and carries away non-ferrous metals continuously and fully automatically. An important factor for good separation is an even flow of material, supplied by a vibrating feeder or conveyor belt, for example, to provide a uniform mono-layer of materials across the belt. It is especially important with smaller fraction sizes.

You may not, except with our express written permission, distribute or commercially exploit the content. Nor may you transmit it or store it in any other website or other form of electronic retrieval system.

a highly hyphenated preparative method with emulsion liquid membrane extraction-in situ magnetization-magnetic separation for bioactive constituents from typical medicinal plant - sciencedirect

Extraction, separation and recovery were integrated in a hybrid route for the first time.In situ magnetic derivatization was achieved in emulsion for selective separation.Main alkaloids and concomitants were enriched in various phases.Phase behaviors, transmembrane process and separation mechanism were explored comprehensively.The whole process was multifunctional, continuous, low cost and highly efficient.

A new emulsion liquid membrane extraction-in situ magnetization-magnetic separation (ELME-ISM-MS) method was developed to extract, separate and recover various compounds (alkaloids, flavonoid and saccharides) from Mahonia bealeias (Fort.) Carr. in a hyphenated way for the first time. Stable water-in-oil-in-water emulsion was prepared in developed circumstances; then water-soluble compounds (e.g. berberine hydrochloride) remained in feed phase; other compounds with weaker polarity entered into the membrane phase, and the lipid-soluble alkaloids (e.g. tetrahydroberberine) reacted with the derivatization reagents of FeCl3 and HCl in the internal phase for subsequent magnetic separation. Phase behaviors, transmembrane process and separation mechanism were all investigated systematically. Such a continuous, highly-efficient and low consumed multifunctional process can benefit sustainable preparation of natural products, which realized extraction, enrichment, separation, purification and recovery simultaneously; the yields of berberine, tetrahydroberberine, rutin and polysaccharides were 67.78, 1.40, 12.58 and 9.88mg/g, separately.

methods of physical separation | separating mixtures | siyavula

'Mixtures' was first introduced in Gr. 6, so learners should already be familiar with these concepts. Learners would have also looked at some of the physical methods of separating different types of mixtures (including hand sorting, sieving, filtration), and this year we will explore some additional methods in more detail (including distillation and chromatography).

In the first section of this chapter, learners will learn how to identify mixtures. One of the central ideas in this section is that the components in a mixture are not chemically joined. They still exist as separate compounds that have not reacted with each other in any way. For that reason, mixtures can be separated using physical methods. Physical methods can not be used to separate elements that are chemically joined.

In order to make this section more interesting you could provide small samples of each of the mixtures discussed and ask learners to draw them, paying close attention to any features that a particular mixture may have. When they are faced with a solution (water and sugar, for instance) they might notice that there are no visible features to draw. This will help establish in their minds that solutions are mixtures where the substances are so intimately mixed (literally on the level of individual particles) that we cannot make out separate substances anymore.

Get your learners to act out the word 'mix'. Learners might make stirring motions with their arms. This exercise may seem trivial but their attention will immediately be focussed (and their learning enhanced) if they are engaged in this way. Using gestures that require learners to move their bodies has been shown to enhance learning even at university level!

Some learners may say no, you need two or more things mixed together to have a mixture. Other learners may answer that it is possible to mix hot water with cold water. Point out that the end result would just be water, and not really a mixture of hot and cold water; once mixed, the water would have the same temperature throughout.

A mixture can contain solids, liquids and/or gases. The components in a mixture are not chemically joined; they are just mixed. That means we do not need to use chemical reactions to separate them. Mixtures can be separated using physical methods alone and that is what this chapter is all about: how to separate mixtures.

This is a revision of the types of mixtures that one can get, which has been done in Gr. 6 Matter and Materials. If you feel your learners have already grasped this, you can go through it briefly by just looking at the different pictures provided and ask learners what types of mixtures they are.

What happens when clay or sand is mixed with water? Would you be able to see through a mixture of clay and water? The mixture of clay or sand with water is muddy. The small clay particles become suspended in the water. This kind of mixture is called a suspension. Suspensions are opaque; that means they are cloudy and we cannot see through them very well.

What happens when sugar is mixed with water? Does the mixture become muddy? Why not? The sugar dissolves in the water and the mixture is called a solution. Solutions are clear; that means we can see through them.

Keep in mind that some mixtures that we expect to be solutions end up being suspensions. A good example is table salt and water that could end up looking cloudy because of the starch (free-flowing agent). In this case it would be better to use pure sea salt. (You could also use this apparent paradox as the basis of an extension activity about what appearances allow us to infer in certain situations.)

Milk is not a single substance, but actually a mixture of two liquids! The one liquid component in milk is water, and the other is fatty oil. The reason milk is opaque is that tiny droplets of the oil is suspended in the water. Can you remember what a mixture is called when a solid is suspended in liquid?

We use milk as an example of a suspension, however, milk is actually more complex since it also contains solutes. It is a great example of a mixture that has both solution and suspension (emulsion) components. Flour or maizena mixed with water also makes a good suspension which settles after some time. This is also a good opportunity to revise the terms solute, solvent and solution, namely the solute (for example sugar) is the substance that is dissolved in the solvent (for example water) to form a solution (for example sugar water).

Are all liquid-liquid mixtures emulsions? (One way to recognise an emulsion is that it is opaque). Are all liquid-liquid mixtures opaque? Can you think of a liquid-liquid mixture that is not an emulsion? Discuss this with your class and give an answer below.

Firstly, no, not all liquid-liquid mixtures are opaque. Secondly, most solutions that learners will be able to think of are essentially solid-liquid mixtures at the fundamental level. It is good enough for learners at this level to offer examples of liquid-liquid mixtures such as 'a mixture of apple juice and water'.

A better example of a liquid-liquid solution is vinegar, which is a mixture of ethanoic acid (acetic acid) - a liquid at room temperature - and water. This example might be a sensible inclusion since it would serve as early introduction to households acids that will feature prominently in the next chapter (Acids and Bases). If learners are given a vinegar sample to draw, it would be better to provide a sample of white vinegar, since it contains less solid matter. Once again they will be confronted with the realisation that the solution does not have visible features. Another opportunity to establish that solutions are mixtures where the substances are so intimately mixed that we cannot make out separate substances anymore.

Solutions are special kinds of mixtures in which the particles are so well mixed that they are not separated from each other. We cannot make out separate substances anymore - everything looks the same when we look with the naked eye.

The particle model of matter will only be dealt with in detail in Gr. 8, but the following kinds of visual representations may aid understanding of abstract concepts. You can draw these on the board with different colours. Learners were exposed to similar images in Gr. 6. However, it is not critical at this stage and you do not need to go into detail. Solutions look glassy/translucent, and the solid particles cannot be seen. The substances cannot be separated by filtration (dealt with later in this chapter).

In a suspension, one of the substance's particles are always clumped together. Sometimes one can even see little globs of oil (in the case of an emulsion) or little lumps of solid (in the case of a suspension) suspended in the liquid.

We learnt in Gr. 6 Matter and Materials that the particles of gases are far apart. This means that gases can mix very easily, because it is easy for their particles to move in amongst each other. The air we breathe is not a single gas but actually a mixture of gases! Do you know what the two most abundant components are?

Nitrogen gas and oxygen gas. Learners may say oxygen and carbon dioxide; nitrogen is actually the main component of air (roughly 80%) followed by oxygen (roughly 18%). Carbon dioxide is present in much smaller quantity.

Can you see the water vapour in the following picture of a boiling kettle? Point to it with your finger. Discuss this with your teacher and classmates and when you have agreed on an answer, draw an arrow onto the picture to indicate the water vapour.

A suggestions is to do a demonstration of this in class if you can get a kettle and plug it in to show learners the colourless steam at the spout of the kettle. Learners may point to the cloud in front of the kettle. This is not actually water vapour, which would be invisible to the human eye. The cloud forms when the water vapour cools down sufficiently to condense into micro-droplets that are visible to the human eye.

We will only see the water when it starts to condense. When the water particles condense, they become liquid water again. That means the particles start clinging together in tiny micro-droplets, which grow into larger droplets when they come together. The small cloud of in front of the kettle is actually a cloud of micro-droplets of liquid water suspended in air. This is an example of a liquid suspended in a gas.

Many things around us occur naturally as mixtures: salty sea water, moist air, soil, compost, rocks (mixture of minerals) to name a few. Many mixtures are man made, for instance; Coca Cola, paint, salad dressing and so forth.

You can ask your learners what we use paint for. Paint is used to cover walls and other surfaces. Sometimes we want to protect these surfaces against water or wind (for instance when we are painting an outside wall or roof) and sometimes we just want to make them look attractive (for instance when we paint an inside wall, or when we create a beautiful artwork). The water or oil in the paint helps us to spread the pigments more evenly over the surface that we want to cover and binds the pigments tightly so that the paint forms a protective layer.

Mixtures are very useful. However, sometimes we need to separate mixtures into their components. Remember that the substances in a mixture have not combined chemically. They have not turned into new substances, but are still the same substances as before - they have just been physically combined. That is why we can use physical methods to separate them again.

As an introduction to this you can ask learners about why they think we would want to separate mixtures. For example, imagine that our drinking water comes from a well in the ground and it is muddy. Muddy water is not good to drink. We would want separate the water from the solid material (sand or clay) before using it! Once separated, we would keep the water to drink and throw the sand away. Ask learners if they can think of a way to separate the water from the sand? Learners may suggest filtration (filtering) as a method for separating the sand and water.

Suppose you were given a basket of apples and oranges. How would you sort them? You would probably pick out all the oranges from the apples by hand. The same method may not be suitable for all mixtures. You would probably not consider sorting sugar and sand grains by hand. Why not?

The video about the Skittles sorting machine is merely for entertainment, but it could be used to introduce discussions on fun 'explorations' and hobbies that challenge us as a starting block for innovation and useful applications of technology.

When we have large quantities of materials to sort and the different particles have different sizes, we can sieve the mixture. The smaller particles will fall through the openings in the sieve, while the larger particles stay behind.

Learners did an exercise in Chapter 6 of Matter and Materials in Gr. 6 on cleaning muddy water. The chapter entitled 'Processes to purify water' required learners to design, make and evaluate their own filter. You can demonstrate the process again to refresh their memories. To set up a filter (as shown below), place a folded piece of filter paper in a funnel and place the funnel into a flask. Then, pour a mixture of muddy water into the filter and let the learners observe that clean water passes through the filter, whilst the mud/sand/clay remains behind.

Sometimes the particles that we want to remove from a mixture are so small that they will pass easily through a sieve (think of the example of the muddy water from before). Can you think of a way to overcome this?

Can you remember the activity from Gr. 6 when Tom used magnetism to separate different kinds of metals at his uncle's junk yard? The magnetic properties of the metals allowed them to be separated in this way.

You could demonstrate how, or let the learners try, to separate a mixture of sand and iron filings by using a magnet. It might help to place the magnet in a small plastic bag so the iron filings are attracted to the magnet, but do not stick to it.

The following diagram shows how magnetic separation can be used to separate a mixture of components. In the example, mineral ore that contains two compounds (one magnetic, and the other non-magnetic) is being separated. The ore grains are fed onto a revolving belt. The roller on the end of the belt is magnetic. This means that all the magnetic grains in the ore will stick to the belt when it goes around the roller, while the non-magnetic grains will fall off the end. As soon as the magnetic grains move past the magnetic roller, they will also fall down.

In the above diagram, what colour are the non-magnetic grains and into which container do they fall? Label this on the diagram. What colour are the magnetic grains and which container do they fall into?

The non-magnetic grains are yellow-orange and fall into the container on the left. the magnetic grains are grey-brown and fall into the container on the right. The diagram should be labelled as follows:

The substances in a solution are mixed on the level of individual particles. In a sugar and water solution, the sugar particles and the water particles are mixed so well that we could not distinguish them with the naked eye. You might think that mixtures that are so 'well-mixed' are impossible to separate! But as we shall soon see, this is not true.

Demonstrate this in a lesson by dissolving some salt in water in front of the class at the beginning of the lesson. Make sure they take note of the clear solution. Then pour a little into a shallow aluminium pan, like those used for baking. Place this out in a sunny spot for the duration of the lesson and allow the water to evaporate. The rate of evaporation will depend on how hot and humid it is on the day you do this. At the end of the lesson, collect the pan and show the dried salt that is left behind, just as in a salt pan. You might have to leave it out until the end of the day, depending in how hot it is.

Do you know where most of the salt that we use in South Africa comes from? South Africa gets it salt from inland salt pans, coastal salt pans and seawater. A salt pan is a shallow dam in the ground where salt water evaporates to leave a layer of dry salt.

When sea water is allowed to stand in shallow pans, the water gets heated by sunlight and slowly turns into water vapour, through evaporation. Once the water has evaporated completely, the solid salt is left behind.

If you have time to do this in class, you can demonstrate this practically. Get learners to taste the salt water before boiling and then getting them to taste the condensed water afterwards. This way they will realise that only the water has evaporated and the salt has remained behind in the kettle. You could put the ice in a small plastic bag to ensure that the ice does not slip off the plate, but the plate is still cold enough for water vapour to condense. Keeping the ice in a plastic bag will also ensure that the melting ice does not drip into the beaker collecting condensed water. You can also use a beaker or glass of salt solution over a bunsen burner and use a cold piece of glass or mirror to condense the water and collect it in another beaker.

In the picture, the salt-water solution is heated in a kettle, and a metal plate (with some ice inside to keep its outer surface cold) is held in the water vapour that is escaping from the spout of the kettle. The water vapour cools when it touches the cold metal plate and condenses. It then runs off the plate and into the collection beaker. The salt is left behind in the kettle once all the water has evaporated. But, you still have the water in the beaker.

What change of state is occurring on the cold surface of the metal plate? What is the process called? (Hint: the change of state from gas to liquid was covered in the previous chapter, under Physical properties of materials.)

The water that is lost through evaporation can be condensed on a cold surface. The cold metal plate will do the job, but it would be difficult to recover all the condensed water, because it will be dripping off the surface of the plate in many different places. Scientists have a solution for that problem: they use a special technique to separate mixtures like these without losing any of the components. The technique is called distillation.

If you have the equipment to set up this distillation process, then you can demonstrate it in class. Otherwise there are alternative materials and equipment that you can use. For example, if you do not have a Liebig condenser, you can use a piece of copper pipe. Here are two links which explain how to build your own distillation equipment: and Another suggestion is to get learners to also do the research to see how to make their own distillation apparatus, specifically looking at materials which are easy and cheaper to come by. You do not have to have laboratory equipment to demonstrate many science experiments - many can just be done by thinking of the materials which you use in everyday life and making a plan! This also makes science more accessible to everyone.

Suppose we want to separate the water and salt in seawater. We would place the seawater in the round flask on the left of the picture (in the distillation flask). We would then boil the seawater to produce water vapour, or steam. The salt would not evaporate with the water, because only the water evaporates. The water vapour rises through the top of the flask and passes into the Liebig condenser.

The Liebig condenser consists of a glass tube within a larger glass tube. The condenser is designed in such a way that cold water can flow through the space between the tubes. This cools the surface of the inner tube. The water vapour condenses against this cold surface and flows into the receiving flask. Since the salt has not evaporated, it stays behind in the distillation flask.

The solar still video is short but provides an interesting topic for discussions: applications of separating methods; inventions; advantages and disadvantages; you could even discuss open-source projects and sharing information. The Italian inventor of the Eliodomestico solar still designed it with developing countries in mind. It is relatively cheap, easy to assemble, and requires no electricity. It is described as an eco-distiller that runs on solar power. All you need to do is pour in 5 litres of salty or impure water, tighten the cap, and leave it out in the sun. By the end of a day it can provide bacteria-free, salt-free water that is suitable for drinking. It is also an open-source project which means that anybody can use the design and replicate, modify or upgrade it, but not sell it for profit.

Ethanol boils at a temperature lower than the boiling point of water, namely 78C. Suppose you mix some water and some ethanol. The mixture is at room temperature to begin with. Now suppose you start heating the mixture. What temperature would be reached first: 78C or 100C?

We can use the same distillation method that we used for separating seawater, to separate the two liquids. The principle is exactly the same, except that we will distill the mixture more than once. Here is how it works:

The mixture of the two liquids is placed in the distillation flask and heated to the lowest boiling point. In the case of an ethanol/water mixture, that temperature would be the boiling point of ethanol, namely 78C. All of the liquid with that boiling point will evaporate, condense in the Liebig condenser, and pass into the receiving flask. The liquid with the higher boiling point will remain in the distillation flask. Suppose it contains a third substance that we want to separate. How would you do this?

We replace the receiving flask with a clean one and heat the distillation flask again, but this time to the boiling point of the second liquid. The second liquid will evaporate, condense in the cooler and flow into the clean receiving flask, leaving the final component in the mixture in the distillation flask.

Crude oil is separated into different components using distillation. The components are evaporated, starting with lighter fuel (which has the lowest boiling point), then jet fuel, then petroleum, then motor car oil, until only tar is left. We call the separated components fractions, and the process, fractional distillation.

The video about distillation of crude oil may be a bit too advanced, but it summarises the process of fractional distillation quite well and mentions relevant, real-world examples of products that are produced. Take note that the video repeatedly mentions 'hydrocarbons'. You can put the learners at ease and tell them it is not important for them to know what this means yet. The periodic table is only dealt with in Chapter 4, but you could help the learners 'decipher' that the crude oil contains a lot of hydrogen particles and carbon particles put together in different combinations (ratios). Each of the fractions that are eventually collected contain one kind of hydrocarbon combination.

Most inks are a mixture of different pigments, blended to give them just the right colour. A pigment is a chemical that gives colour to materials. When a mixture contains colourful compounds, it is often possible to separate the different components using a separating method called chromatography. Let's have a look at this next.

This is a fun activity that can be done quickly. If the class is divided into small groups and each group gets a different black marker to experiment with, the chromatograms can be stuck up on the wall afterwards for everyone to see and compare. By looking for matching chromatograms, learners can say which group had the same brand of marker, or which markers are filled with the same ink. If the ink from a certain marker will not separate in one liquid, try using another liquid in the beaker.

You could even build a story around the investigation: Stage a murder mystery in which the murderer can be identified by his (or her) black pen. Use three or four black or blue pens of different brands, and produce the unique chromatograms associated with each brand. The inks may look the same when used for writing, but they will behave differently when they are analysed by chromatography.

Laboratory Whatman filter paper no. 1 is ideal for chromatography. Alternatively, you can use coffee filters, watercolour paper or strips of paper towel. Even ordinary copy paper works, but more slowly and often this makes the colours separate better. For softer papers you may need longer strips of paper and taller containers, since the liquid is carried up the paper much faster.

Safe laboratory practice is extremely important. Take a moment to discuss risks, precautions and safety with learners. Discuss the fact that scientists often need to handle dangerous substances and/or equipment to be able to make observations.

When working with ammonia, take care to work in a fume hood or in a well-ventilated space. Leave the door and windows open, so that the fumes do not linger. Similarly, substances containing alcohol should be used in a well-ventilated space, but these are also flammable, so avoid using them in the presence of open flames.

It is always advisable to wear latex/nitrile gloves (available from pharmacies) to prevent the absorption of hazardous substances through your skin. Wear safety goggles to protect your eyes from harmful chemicals. Always have clean water nearby to rinse your eyes or wash your hands if chemicals do splash or spill.

The pigments in the ink are carried along by the liquid, but because they are different compounds, they get carried upward at different speeds. This causes them to appear as bands of different colours on the chromatogram.

Pigments migrate at different speeds because of differences in their properties: large pigment particles tend to move more slowly. Furthermore, particles that dissolve well in the liquid will tend to stay in the liquid and be carried to the top quickly, while particles that bind well to the paper will tend to move more slowly.

Some schools also use combo plates for the various practical tasks in Matter and Materials. This is encouraged and the activities in these workbooks can be adjusted slightly to work with whichever equipment and apparatus you have available to you in your school.

Also, if learners find the flow chart too complex at this stage, you can alternatively get them to write out the steps they would follow to separate all the materials in the mixture and why they have chosen each method of separation.

Imagine you are a member of a team of scientists working together in a laboratory. Your team has been given an important job. You have been given a beaker that contains a mixture of substances to separate.

This may be a difficult task for the learners to accomplish, but it is very important for the learners to be able to visualise the mixture before they start to plan the experiment. If they do not, the ideas will remain abstract and the learners may have difficulty sequencing the different separation steps correctly. You could guide them by asking the following questions. Alternately, you could prepare the mixture for them to look at it before drawing it:

So far, we have been discussing materials, their properties, how to mix them and how to separate them if they are mixed. The final section of this chapter deals with waste materials and what we can do to reduce their impact on the environment.

Over time, some of our things get old and break and we need to throw them away. When we buy food or other items, the packaging used for wrapping these items is also thrown away. But what does 'away' mean? Does it mean these waste items just disappear? Where do you think our rubbish goes once we 'throw it away'?

Allow learners to discuss this for a while. Some may know that rubbish eventually ends up on a rubbish dump somewhere, and this is a good starting point for the next activity that will require learners to think about the implications of dumping.

'There is no away' and 'There is no Planet B' refers to the same issue, namely that everything that we throw away remains part of our environment. We should be thinking of ways to reintegrate our waste by making it part of the environment in ways that will not harm the environment; reusing, recycling and repurposing waste items and materials in creative and innovative ways. 'There is no Planet B' is also a play on words that refers to the well-known notion of a 'Plan B' that can be reverted to if the original plan (plan A) fails.

Many things can be reused or recycled. Many of the waste that is not recyclable can be turned into compost for the garden. Learners may have interesting opinions about this question, and hopefully it will get them thinking about creative ways of reusing and repurposing waste.

For this activity, learners must use materials that would ordinarily go into the rubbish bin in your home (cereal boxes, cardboard, plastic wrappers etc) to make a poster that will create awareness for the environmental problem that concerns them the most. The poster should also contain suggestions for solving the problem. Here are a few ideas, but they only need to choose one:

In some suburbs, recycling is actively encouraged and special transparent recycling bags are provided for this purpose. Do you have recycling in your community? Is the recyclable waste collected from your home or do you have to drop it off at a container or a depot? Did you know that some people even make money selling recyclable waste that they collect?

In this short activity, we are going to think about creative ways of dealing with household waste items that are not in the 4 categories discussed above. For each item in the table, some recycling ideas have been given.

Invite a chemist/scientist: Do you know someone who is a chemist or a chemical engineer? Perhaps you live near a university? If you do, you could invite a chemist to come to your school and talk to your class about the work that chemists do. Alternatively, you could visit the chemist at their workplace and ask them to show you around. You can get learners to prepare a few questions beforehand; for instance, you could ask them about their work, their training and what they think are the qualities needed if one wanted to become a chemist. Just remember to make an appointment first!

Chemists study various chemical elements and compounds, their properties and how they react with each other. We will learn about elements and compounds in the next chapter. Chemists are also responsible for developing new materials with specific properties; such as new medicines; innovative materials for building buildings and other structures; materials that could be used for making fuels from renewable sources and many others.

If you study chemistry after you have finished school, you can work as a researcher, a laboratory technician, a science teacher and many other important and stimulating jobs! Be curious and discover the possibilities! Science can help us solve problems in the world around us.

This is not for assessment purposes and is aimed at getting learners to start thinking about the possibilities for their futures. The emphasis should be on discovering the possibilities that science, technology maths and engineering give us, not just work opportunities, but using them to solve problems in the world.

A useful site to find out more about some chemistry-related careers.

We looked at physical methods to separate mixtures and these are shown in the concept map. Give an example of the types of mixtures you could separate using three of these methods. What negative consequences does human waste have on the environment? Fill these in the concept map.

Two important words have been left out of the following paragraph. The missing words are chemical and physical. Rewrite the sentences and fill in the missing words in the paragraph by placing each one in the correct position:

The components in a mixture have not undergone any _____ changes. They still have the same properties they had before they were mixed. That is why mixtures can be separated using _____ methods. [1 mark]

A vacuum cleaner creates a suspension of dust in air as it sucks up the dust on the floor. Clean air comes out of the vacuum cleaner. How does the vacuum cleaner separate the dust from the air? [2 marks]

The vacuum cleaner has a fine filter in it which traps the dust particles. The clean air is able to get through the filter, but the dust is left behind. Some more modern vacuum cleaners also filter the air through water which cleans the air even further. Some very fine dust particles may be able to get through the fine filter, but if the air is passed through water, then even very fine particles are trapped.

All Siyavula textbook content made available on this site is released under the terms of a Creative Commons Attribution License. Embedded videos, simulations and presentations from external sources are not necessarily covered by this license.