---About diamond

   Usually Diamond price increased basis on particle size , therefore the diamond must be lossless recovery, so when you screening diamond and other minerals, Not only need use conventional ways to crush and grind small particles, but also need manually . Diamond dressing process generally includes: preparation, roughing and cleaning stages.  

   First, preparation stage: Before diamond dressing preparatory work including crushing, screening, washing ore, grinding, hydraulic classification. The purpose is to create good conditions for ore dressing, so that the separation operation can be carried out smoothly and achieved good results.

   Second, diamond roughing: Diamond ore after crushing, screening, washing, grinding, classification and other preparatory work, it means into the benefication work. Diamond dressing is usually divided into two stages.,the first stage is coarse selection, which mainly plays an initial role in enrichment,the task is to separate a little containing diamonds of heavy minerals and a lot of without diamonds of light minerals, and finally to obtain containing diamonds of rough concentrate. There are three commonly roughing methods: panning, dressing, jig dressing and heavy medium dressing.

   Third, selection: the task is further processing rough concentrates , until diamonds is picked.

Ⅰ:Preparation stage

1.Crushing
   Crush is a main work before sorting diamond primary ore. In the crushing stage, on the one hand should make a full dissociation of the coarse ore, on the other hand, as far as possible to reduce broken diamond crystals, in the process of ore crushing, protection of crystals is more stringent than crushing other minerals. Crushing equipment is mainly jaw crusher, cone crusher, hydropower crusher ect.
2. screening
    In diamond dressing,it is need lots of screening operations . On the one hand can timely screening out the appropriate size of ore in the crushing stage, avoid excessive crushing, reduce power consumption, improve efficiency, but also helps to protect the crystal: on the other hand can prepared for the next step. The screening equipment is screening machine, the most commonly used is vibrating screen, secondly shaker screening.
3.ore washing
   Diamond placer and some primary ore containing a large amount of clay minerals in the ore, which must be removed before beneficiation . The ore washing is remove clay material processing , including two stages,is clay dispersion and make dispersed clay material separated from the granular material. The ore washing equipment used a water cannon, drum washer, tank washer and so on.
4.Grinding
   Grind is continue to the crushing process, means in the mechanical equipment, by means of the medium and the ore itself impact function and grinding function, make size of ore become smaller . The main purpose of diamond ore grinding is to separate the whole or most of the small diamonds from the ore, so that recover them in the next step. In addition, according to the diamond and rocky minerals wear resistance difference, selective grinding, Most ore can be grinding to the target granularity,discarding tailings and improving efficiency. Grinding usually work in a rotating cylindrical mill. The grinding machine has ball mill, rod mill and autogenous mill,basic principle is to use the medium (or ore itself) impact ore to grinding each other.

5. Hydraulic classification
   When separation small material, because screening has difficult, we often use the way of hydraulic classification. Its work principle is based on the difference in the settling velocity of the particle size (or density) in the fluid. The main equipments used in hydraulic classification are spiral classifier and hydrocyclone.

Ⅱ:Roughing stage

    After crushing, screening, washing, grinding, classification and other preparatory work, Diamond ore begin to mineral processing operations

   In1874,washing pan instead of washing groove become a unique diamond sorting equipment has been widely used. Africa more than 100 old mine had used it for diamond initial enrichment , although now replaced by the heavy medium separation, there are still some old mines remain it. washing pan sorting principle is according to the difference of mineral density, Diamond and a little high density minerals stay in the pan bottom, low density ore discharged from the overflow weir, so as to achieve purpose of according different density to separation.Washing pan advantages is: simple structure, convenient operation, when you used for washing,meanwhile has sorting function.

   Main processing method of diamond mines in China. Its basic principle is due to differences in diamond and ore density, shape, surface friction coefficient,in a vertically alternating moving medium flow, the material will be stratified accord density. Diamonds not only has great density, but also rounded shape, smooth surface, with the fast settling velocity and great wear ability ,Therefore, it is easy to form concentrates. Separating medium commonly used water. Achieve Jig sorting result equipment is jigging machine, is mainly composed of a water tank with sieve and a piston or a diaphragm which causes water to generate vertical alternating motion, and rotating mechanism for driving piston and diaphragm movement. When the ore particles are layered on the sieve, the light minerals above are discharged with the horizontal flow through the overflow weir, and the heavy minerals below are discharged under the sieve. The advantages of jigging dressing are good separation effect, simple process, convenient operation and management, but the equipment production has disadvantage with low capacity , water consumption, sorting efficiency is not as high as the dense medium.

    Way for rough selection of a diamond is widely used in abroad. The basic principle is based on Archimedes's law, gravity of object in a liquid is proportional to the volume of liquid, density of ore particles and media, Ore particles whose density is greater than the density of the selected medium will precipitate in the medium and concentrate at the bottom of the separator; density of ore particles is less than the medium particles will float on the top layer of the medium and will be gathered on the surface of the separator. The two minerals will be removed from the separator, mean obtain has different density of product.Therefore, in the heavy medium separation, law of layered ore particles, only depends on the density of ore particles heavy medium in cyclone, it has nothing to do with its size and shape. But their layering speed is a function of particle size and density difference between mineral particles and medium, The size is larger and the density difference is higher, faster sorting, sorting time is short. Heavymedia separation has two kinds of medium : heavy liquid and heavy suspension.

 

Ⅲ:Concentration stage

     The task is further processing rough concentrates , until diamonds is picked. The rough selection of diamonds is usually made by gravity dressing, which is due to the low ore content of diamond ore . First,It is economically more cost-effective to use the method of gravity separation with lower production cost than other beneficiation methods. After roughing diamond ore obtained mixture of diamond and heavy minerals, the diamond content is still low. In order to obtain diamonds, the coarse concentrates must be further selected to separate the diamond from the heavy minerals and finally get separate diamond. The commonly used methods of diamond selection are manual hand sorting, X photoelectric dressing, oil dressing, magnetic separation, surface flotation, heavy liquid dressing, etc..