How is apatite mined

These biological Apatites are almost exclusively the Hydroxylapatite type. The hexagonal crystal system designation is due to a hexagonal symmetry of most Apatite. However, positional ordering of chlorine atom s or the hydroxyl radical in Chlorapatite and Hydroxylapatite can lead to monoclinic symmetry.

Apatite generally forms as well-shaped hexagonal crystals, which may be prismatic , dipyramidal , and stubby. Also as flat, tabular plate s, columnar , in stacked parallel growths, as globular masses, acicular , grainy , stalactitic , botryoidal , and earthy.

Also in enormous beds of massive material, from which industrial phosphorus is mined. Carbonate apatite. Also known as Carbonate-rich Apatite. Important Apatite localities in Europe include Ehrenfriedersdorf, in the Erzgebirge, Saxony, Germany, a classic locality which is also the type locality for this mineral. Panasqueira, Portugal, is well-known for its thick and gemmy tabular Apatite crystals. Deep blue crystals come from Sludyanka, in Lake Baikal area, Russia; and interesting forms, especially botryoidal , come from the Lovozero Massif, Kola Peninsula, Russia.

Beautiful greenish-yellow Apatite with a excellent luster and transparency have been coming from the Imichil area in Morocco.

One of the most famous localities of Apatite is Cerro de Mercado, Durango, Mexico, where gemmy prismatic crystals are plentiful. In the U. Rubellite Quarry in Hebron, Androscoggin Co. The Acushnet Quarry in Bristol Co.

Beautiful pink and purple crystals with excellent transparency have come from the Foote Mine, Kings Mountain, Cleveland Co. Light blue crystals have come from the Butte mining district, in Silver Bow Co. Let us know how we can update this page Click for more details. We strive for accurate content and locality information. The particle-particle contact between different particles results in the transfer of electrons charges from the surface of one particle to the surface of the other one.

After this transfer, one of the particles is positively charged and the other one possesses the negative charge. The separation zone consists of two vertical walls of rotating tubes, which oppose each other and which are electrified by opposite potential. As the charged particles enter the separation zone, they become attracted by oppositely charged electrodes. The separated products are collected at the base of separator. This separator removes very effectively silica from other nonconductive minerals, such as calcium carbonate, phosphate and talc [ 15 ].

Operating principle of electrostatic separator: a V-stat separator, b plate-type separator and c roll-type separator [ 15 ]. In the horizontal belt-type separator, fast-moving belts travel in opposite directions adjacent to suitably placed plate electrodes of the opposite polarity.

The material is fed into a narrow gap between two parallel electrodes. The electric field attracts the particles up or down depending on their charge. The moving belts transport the particles adjacent to each electrode towards opposite ends of the separator [ 15 ].

In , a patent was filed by William Fullarton describing the separation of iron minerals with a magnet. The background for electricity and magnetism, the reasons that magnets could move materials, were explained by Gauss and Helmholtz [ 18 ]. Electromagnets almost completely replaced permanent magnets as the field-generating elements in drum separators [ 20 ]. Recent progress in magnet technology has realized economically and operationally favorable cryocooler-cooled 5 All superconducting devices share the need for sufficient refrigeration to overcome their low-temperature heat loading.

This loading comes typically in two forms: 1 heal leaks from the surrounding and 2 internal heat generation in the device. In addition, the refrigeration system needs to bring the superconducting device from ambient temperature to its low operating temperature in reasonable length of time [ 21 ].

His follow-up discovery of superconductivity in introduced the zero electrical current resistivity to the world. It was theorized that one could go beyond the resistive limit of a copper wire to develop a superconductor that could carry any amount of current but without the ohmic loss [ 23 ].

Drum separator using a multi-pole superconducting magnet Klochner Humbolt-Deutz Cologne, Germany [ 22 ].

Despite all this progress, the majority of the commercial magnetic separators fulfill only the simple technological objective of the removal of magnetic substances without the ability to classify them. Only three classical separation products tails, middlings and mags, Fig. Classical magnetic separation products [ 25 ]. Unlike the conventional filtration methods that use the blocking-type filtration, the secondary waste is not produced in high-gradient magnetic separation HGMS , which is also known as the magnetic or electromagnetic filtration.

Furthermore, because HGMS systems use much higher magnetic forces than conventional magnetic separation techniques, it can also be used to separate rapidly large quantities of diluted suspension [ 22 ].

According to the applied separation method, two classes of magnetic separators are recognized [ 26 ]: Separators that deflect the magnetic particles from the main stream, e.

Separators that usually collect the magnetic particles in matrices, e. Although current separators usually achieve high grades of separation, they cannot classify the particles 7 Differential magnetic classification and the selectivity are different definitions.

The selectivity is defined as the ability to separate one certain kind of magnetic particles from all others, independently of how close their magnetic susceptibilities may be [ 25 ]. Magnetic separation has been considered for many years a valuable method to achieve the purification of streams of particles dry or wet [ 26 ].

Magnetic separators have unrestricted industrial applications and are widely used in mineral beneficiation, food, textiles, plastic and ceramic processing industries. The separation efficiency of magnetic separator depends on the material characteristics and the design features of equipment along with the optimization of process variables [ 27 ].

The magnetic force on a particle is then proportional to the magnitude of magnetic flux density and the gradient. The magnetic field can be increased using a stronger magnet having more ampere turns, and the field gradient can be increased by changing the magnetic polarities and using a steel wool matrix. For sufficiently strong magnetic particles such as iron, magnetite and maghemite, it is advantageous, and Eq. The basic principle behind magnetic separations is remarkably simple and remains unchanged from these early examples.

It is based on a simple fact that materials with differing magnetic moments experience different forces in the presence of magnetic field gradients; thus, externally applied field can hand pick the components with distinctive magnetic characteristics out of physically similar mixtures [ 18 ]. When one of the major gangue constituents is magnetic, magnetic separators are used as one of the steps in the flow sheet to remove the magnetic constituents.

This is mostly used in the beneficiation of igneous phosphate rocks. However, it was also used for the beneficiation of some sedimentary phosphate ores [ 1 ]. Typical magnetic pulley a and magnetic drum operating as lifting magnet b [ 15 ]. Paramagnetic minerals have higher magnetic permeability than the surrounding medium, usually air or water, and they concentrate the lines of source of an external magnetic field.

The higher the magnetic susceptibility, the higher the field intensity in the particle and the greater the attraction up the field gradient toward increasing field strength.

Diamagnetic minerals, on the other hand, have lower magnetic permeability than the surrounding medium and they repel the lines of force of magnetic field. These characteristics cause the expulsion of diamagnetic minerals down the gradient of the field towards decreasing field strength.

This negative diamagnetic effect is usually orders of magnitude smaller than the positive paramagnetic attraction. Thus, a magnetic circuit can be designed to produce higher field intensity or higher field gradient or both to achieve the effective separation [ 15 ]. Magnets are used in the mineral industry to remove the tramp iron that might damage the equipment and to separate minerals according to their magnetic susceptibility.

High-intensity magnetic separators separating paramagnetic or weakly magnetic particles require higher flux density. This higher density is achieved by designing the electromagnetic circuitry that can generate the magnetic force of up to 2 tesla. For example, in a silica sand processing plant, these separators are used to remove weakly magnetic iron-bearing particles.

Rotating-drum magnetic separators Fig. The rotating disc magnetic separator is used in so-called ferritic processes [ 22 ]. The removal of carbonates from phosphate rock has been the focus of significant research efforts. The calcination of phosphate ores to remove carbonates is expensive because of high costs of energy. Calcination is practiced commercially at several phosphate rock mining operations around the world, mainly to improve final product quality by removing minor amounts of carbonates and organic matter.

Calcination is also used to remove carbonates where the cost of natural gas is very low [ 1 ],[ 6 ]. Calcium and magnesium carbonates are readily dissolvable in both mineral strong acids and organic acids weak acids.

In the case of calcareous phosphate ores, although mineral acids dissolve carbonates at high reaction rates, they also attack the phosphorus-bearing minerals and cause losses in the P 2 O 5 content of the ore; hence, they are not appropriate if the intention is only to beneficiate the ore not to dissolve phosphates. To avoid this problem, organic acids were studied as carbonate leaching agents, although their reaction rates are low.

These organic acids may be expensive and will certainly add to the production cost. On the other hand, they are selective to leaching carbonates, their capital cost is low, they do not cause environmental hazards and they can be recycled [ 1 ]. The organic acids most commonly used in carbonate leaching are acetic acid, citric acid and formic acid.

They are used for some specific advantages may be the cost, availability, etc. Suggested reaction between acetic acid and carbonates is [ 1 ],[ 16 ],[ 29 ]:.

The dissolution kinetics of calcareous material with acetic acid solution was found to fit the shrinking core model for the reaction-controlled process. The activation energy was determined to be Acetic acid may be recovered by reversing the above reaction at high CO 2 pressure in a separate reactor or by using sulfuric acid to precipitate calcium sulfate and to liberate acetic acid:.

Similarly, formic and lactic acids Eq. Traditionally, the heat treatment of phosphate ores is defined as heating up the ore to a certain temperature to obtain a product with specific properties. The main processes that take place during the thermal treatment of apatite ore are [ 1 ],[ 3 ],[ 31 ],[ 32 ]: Drying , i. Thermal decomposition of carbonates , i. Removal of fluorine , i. The calcination process of phosphate ore is schematically shown in Fig.

Illustration of the defluorination process of phosphate rocks [ 1 ]. There are various types of units that can be used for the calcination of phosphate ores, such as [ 1 ]: Vertical-shaft kilns [ 33 ],[ 34 ]: are the most popular type of kilns, having varying heights, diameters and constructional details.

There are two types, namely mixed- a and unmixed-fuel type b. The construction of a vertical shaft may be cylindrical, conical or a combination of both shapes with varying diameters in different zones Fig.

Fluidized-bed reactors calciners [ 33 ],[ 34 ]: the hog gases perform two functions: 1 fluidize the particles and 2 transfer the heat to the particles Fig. Since the fluidization is a function of particle size, only fine particles can be introduced as the feed particles. Schematic diagram of annular-shaft kiln a and fluidized-bed calciner b [ 34 ]. Rotary kilns 9 Rotary kilns are synonymous with cement and lime kilns probably because of the history of their evolution and development.

Schematic representation of countercurrent flow rotary kiln [ 34 ]. The rate of movement of the material through the kiln may be estimated using several relationships, e.

Since the rotary kiln is divided to zones, the relationships should, more appropriately, be used for several reasonably uniform zones along the kiln and the total residence time can be calculated as the sum of the residence times for the individual zones. Traveling grate-kilns, rotary kilns systems [ 36 ],[ 37 ]: use low strength, somewhat wet pellets. When cut en cabochon with the silk oriented parallel to the bottom of the stone, these specimens will often exhibit a chatoyance known as "cat's eye.

As a gemstone, apatite is more popular with gem collectors than it is with jewelry buyers. The mineral has a Mohs hardness of 5, breaks with parting, and is very brittle. These characteristics make it too fragile for use in most types of jewelry. Transparent specimens with excellent clarity and vivid color are used as gemstones.

Brittle, often highly fractured. Can be scratched with a steel knife blade. Chemical Composition A group of calcium phosphates. Serves as a hardness of 5 on the Mohs Hardness Scale. Find Other Topics on Geology.

Maps Volcanoes World Maps. Green, brown, blue, yellow, violet, pink, colorless. Mohs Hardness. Color, crystal form, and hardness. A group of calcium phosphates. Fertilizer, phosphoric acid, hydrofluoric acid, gemstones, ore of rare earth elements, pigments, gemstone. Rock and Mineral Kits. Are Water and Ice Minerals? Mohs Hardness Scale.

Apatite is critical both to our physical well-being and our global food supply. In the form of apatite, phosphorus is essential to plant life for growth and photosynthesis, and to animal life as a vital component of genes, teeth, bones, and muscles. Fluorapatite, the hardest, most durable and abundant, of the three apatite minerals, is the primary component of vertebrate bones and teeth. When fluoride compounds are added to drinking water and toothpaste, fluorine ions displace chlorine and hydroxyl ions to convert chlorapatite and hydroxylapatite to fluorapatite , thus improving the decay-resistance of teeth.

Although collectible apatite crystals occur in hydrothermal deposits and granite pegmatites, most apatite exists in the form of collophane. This microcrystalline or massive form of apatite is a major component of marine sedimentary rocks deposited by ancient seas. The collophone supported large populations of plankton and other tiny, invertebrate organisms—the phosphorus-rich remains of these organisms mixed with sea-bottom sediments eventually lithified into phosphate rock.