Mineral processing plant can involve four general types of unit operation: Crushing – particle size reduction; Sizing – separation of particle sizes by screening or classification; Concentration by taking advantage of physical and surface chemical properties; Dewatering – solid/liquid separation.

Sizing (Screenin) Process

Sizing is the general term for separation of particles according to their size.
The simplest sizing process is screening, or passing the particles to be sized through a screen or number of screens. Screening equipment can include grizzlies, bar screens,wedge wire screens, radial sieves, banna screens, multi-deck screens, vibratory screen, fine screens, flip flop screens and wire mesh screens. Screens can be static (typically the case for very coarse material), or they can incorporate mechanisms to shake or vibrate the screen.

Some considerations in this process includes the screen material, the aperture size, shape and orientation, the amount of near sized particles, the addition of water, the amplitude and frequency of the vibrations, the angle of inclination, the presence of harmful materials, like steel and wood, and the size distribution of the particles.

Concentration Process

There are a number of ways to increase the concentration of the wanted minerals: in any particular case the method chosen will

depend on the relative physical and surface chemical properties of the mineral and the gangue. Concentration is defined as the

number of moles of a solute in a volume of the solution.

Dewatering Process

Dewatering is an important process in mineral processing. The purpose of dewatering is to remove water contained in particles. These processes increase in difficulty and cost as the particle size decreases.

Dewatering screens operate by passing particles over a screen. The particles pass over the screen while the water passes through the apertures in the screen. This process is only viable for coarse ores that have a close size distribution as the apertures can allow small particles to pass though and are not able to be produced for small particles.
Sedimentation operates by passing water into a large thickener or clarifier. In these devices, the particles settle out of the

slurry under the effects of gravity or centripetal forces. These are limited by the surface chemistry of the particles and the size

of the particles. To aid in the sedimentation process, floculants and coagulants are added to reduce the repulsive forces between the particles. This repulsive force is due to the double layer formed on the surface of the particles. The floculants work by binding multiple particles together while the coagulants work by reducing the thickness of the charged layer on the outside of the particle.
Thermal drying is usually used for fine particles and to remove low water content in the particles. Some common processes include rotary dryers, fluidised beds, spray driers, hearth dryers and rotary tray dryers. 

What methods are used in the Mineral Processing Plant 

Gravity Method
Particles can be classified based on their specific gravity. Air is the main fluid medium used for the process. Gravity

concentration processes include: heavy media or dense media separation (these include, baths, drums, larcodems, dyana whirlpool separators, and dense medium cyclones), Shaking tables, such as the wilfley table, Spiral separators, Classifier, Batac jigs, Centrifugal bowl concentrators, such as the Knelson concentrator. Jig concentrators are continuous processing gravity concentration devices using a pulsating fluidized bed.

Froth Flotation Method

Froth flotation is an important concentration process. This process can be used to separate any two different particles and

operated by the surface chemistry of the particles. In flotation, bubbles are introduced into a pulp and the bubbles rise through

the pulp. In the process, hydrophobic particles become bound to the surface of the bubbles. The driving force for this attachment is the change in the surface free energy when the attachment occurs. These bubbles rise through the slurry and are collected from the surface. To enable these particles to attach, careful consideration of the chemistry of the pulp needs to be made. These considerations include the pH, Eh and the presence of flotation reagents. The pH is important as it changes the charge of the particles surface and the Eh affects the chemisorption of collectors on the surface of the particles. Flotation machines are widely used in this process of mineral processing plant

Electrostatic Separation Method

 There are two main types of electrostatic separators, they are electrodynamic separators (or high tension rollers) or electrostatic separators. In high tension rollers, particles are charged by a corona discharge. This charges the

particles that subsequently travel on a drum. The conducting particles lose their charge to the drum and are removed from the drum with centripetal acceleration. Electrostatic plate separators work by passing a stream of particles past a charged anode.

These separators are used for particles between 75 and 250 micron and for efficient separation to occur, the particles need to be dry, have a close size distribution and uniform in shape. Of these considerations, one of the most important is the water content of the particles. This is important as a layer of moisture on the particles will render the non-conductors as conductors as the layer of the water is conductive.
Electrostatic plate separators are usually used for streams that have small conductors and coarse non-conductors. The high tension rollers are usually used for streams that have coarse conductors and fine non-conductors.

Magnetic Separation Method

There are two main types of elect Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet. In mines where wolframite was mixed with cassiterite, such as South Crofty and East Pool mine in Cornwall or with bismuth such as at the Shepherd and Murphy mine in Moina, Tasmania, magnetic separation was used to separate the ores.

In this machine the raw ore, after calcination was fed onto a moving belt which passed underneath two pairs of electromagnets under which further belts ran at right angles to the feed belt. The first pair of electromagnets was weakly magnetised and served to draw off any iron ore present. The second pair were strongly magnetised and attracted the wolframite, which is weakly magnetic. These machines were capable of treating 10 tons of ore a day.This process of separating magnetic substances from the non-magnetic substances in a mixture with the help of a magnet is called magnetic separation. This process operates by moving particles in a magnetic field.  

 What machines are used in the Mineral Processing Plant? 

1. Jaw Crusher
Jaw Crusher is ideally suitable for primary crushing, as the most popular stone-crushing equipments, it is widely used in mining, metallurgy, construction material, highway, railway, hydroelectricity and chemical industry for crushing various materials with compression strength less than 330 Mpa.

2. Cone Crusher
Cone Crusher series Composite cone crusher get to world advanced level, absorbing word advanced crushing technology, it is widely used in metallurgical, aggregate, building material industries, it is suitable for crushing varies of hard and above mid hard ores and rock.

3. Vibrating Screen
Yufeng vibrating screen with circular motion is specially designed for quarry to separate crushed stone material into

different sizes, and is also used as a grading machine in coal dressing ore dressing, construction material electric and chemical industries. It has a feature of advanced structure powerful vibrating forces low vibration noise, easy maintenance high durability, etc.

4. Ball Mill
This machine is a skeleton pattern ball mill with horizontal cylindrical turning gear, drive by outer gear and two hoppers. The

material goes to the first hopper after the spiraling by the quill shaft from the feeding equipment. The hopper has ladder

sheathing or corrugated sheathing with steel balls inside, which will fall under the effect of centrifugal force by barrel turning

to ram hard and grind material. After the kibbling in the first hopper, by monolayer partition panel

5. Spiral Classifier
We produce high weir type, single and double spiral, and immersed single and double spiral classifiers. Our spiral classifiers are widely used in the separation of ore in closed circuits with ball mills, grading ore and fine slit in gravity mills, grading

granularity and flow of metal ore-dressing, and de-sliming and dehydrating in washing.This product features simple structure,

reliable working conditions and convenient operation. Because different grains have different specific gravity.

6. Magnetic Separator
The China Magnetic Separators are available in cyclic design with process vessel diameters smaller than 3mm. Magnetic Separator is one kind of efficient equipment for processing fine, feebly magnetic minerals, such as hematite, limonite, wolfram, ilmenite, and tantalum-niobium, etc. In recent years, it is also more and more applied in purifying quartz, feldspar and nephline. Its magnetic system is a ring-shape chain closed magnetic circuit with energizing coils made of copper tube and cooled internally by water. Grooved plates made of magnetic conductive stainless steel are used as magnetic matrix.

7. Flotation separator
 Ore flotation equipments applicable for the separation of nonferrous metal and ferrous metal and nonmetal, such as fluorite and talc. The impeller is driven by V-belts, which can bring the centrifugal effect to form the negative pressure. On the one hand, to inhale sufficient air to mix with ore pulp; on the other hand to stir ore pulp and mix with medication to form the mineralized froth. To adjust the height of flashboard to control the liquid level and make the useful froth scraped by loam board.

8. Concentrator
The High efficiency concentrator machine of our company is suitable for dehydrating water of the concentration and gangue in the concentrating factory, make the mash of 20-30% raise up to 40-70% about. It is widely used for melting, chemical, coal, non metal concentration, environment protected etc industry.
 

9. Mixer
This machine rotaries by the V-belt drives the impeller, make medicine and mash mix even engough, increase the medicine effect time, strength the medicine effect quantity, necessity set. It fits concentrating, and every chemical industry mixing.Before the machine starts, the bolts on the machine body shall be fixed firmly. Turn the axis to check the flexibility. And then start the

machine. The rest instruction is the same to flotation machine.

10. Shaking Table
Shaking table is one of the mineral separation equipment of gravity concentration. It is easy to be operated and can produce high grade concentrated ore, secondary concentrated ore, middlings and gangue, etc at the same time. It is widely used to separate tungsten, stannum, niobium, other rare metal and noble metal ores; it can also be used to separate iron, manganese minerals, coal, and so on.

11. Spiral Chute
Gravity spiral chute is our company's concentrating experienced scientific product, The product is made of the fiberglass lined

with wear-resistant polyurethane and corundum cover; the advantages are light, moisture proof, anti-rust, wear proof, anti

corrosion and no noise, properly suitable for granularity 0.3-0.02 millimeters fine grain

12. Dryer
Rotary dryer is used for drying materials with humidity or granularity in the industries of mineral dressing, building material,

metallurgy and chemical. Rotating dryers can be used for drying many kinds of materials and with convenient and reliable operation; therefore, it has been widely used.