RU2237519C1 - Method of concentration of diamonds at ore benefication stage - Google Patents

Abstract

FIELD: concentration of diamonds.

SUBSTANCE: proposed method includes crushing of diamond-containing material in crushers provided with slots whose diameter is no less than 2.5 diameters of maximum initial lump; it is provided with locking unit at control of rate of unloading of crushed material from crusher; delivery of initial material is discontinued till complete use of material in bin. Crushed product is fed to screen ensuring passage of 20-35% of crushed material per crushing stage at various rates of unloading. The oversize is directed to bin and then again to crusher, thus forming circulation of the oversize in closed cycle till required concentration of diamonds has been obtained.

EFFECT: enhanced efficiency.

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Description

The invention relates to the enrichment of mainly diamonds and can be used for processing foundry slag, electrolyte crust and many other materials whose components are hard.

Comparatively sophisticated diamond processing technologies are known that are based on not so stable distinguishing features (luminescence, contact angle, etc.) as their hardness, with the same need to open crystals by crushing and grinding the whole ore to a certain size (Fishman M.A., Zelenov V.I. Practice of concentration of ores of non-ferrous and rare metals.M .: Nedra, 1967 T. 5).

The objective of the invention is the associated concentration of diamonds in the process of ore preparation - disclosure of crystals.

The problem is achieved in that in the method of concentrating diamonds at the ore preparation stage, including crushing diamond-containing material in a crushing crusher with an unloading slot of at least 2.5 diameters of the maximum initial piece, equipped with a locking device installed with the ability to control the rate of discharge of crushed material from the crusher, according to the invention, the feed to the hopper is stopped until the entire mass is fully developed from it, the crushed product is fed to a screen, about effectiveness to extend from 20 to 35% of crushed material in a single step cleavage at different speeds discharge from the crusher, and the oversize product is sent to a hopper and further back to the crusher, forming circulation crushed oversize product in a closed loop with a crash to the required therein diamond concentration.

The inventive method is as follows. In the process of crushing kimberlite in the grinding mode (for example, according to the crushing method according to patent RU 2075173 C1, B 02 C 1/00, 2/00 of 02.22.94), less solid minerals are crushed first of all. When the material crushed in this way is sieved, the predominant minerals remain (concentrate) mainly the hardest minerals and the hardest of them are diamonds. By repeating the crushing of the oversize product in a closed cycle with a roar, the desired concentration of diamonds in the final oversize product is achieved.

The goal is achieved by the totality and sequence of the following techniques (processes):

- fill one of the minimum of two bins, for example N1, with the source material and stop supplying this material to it until the entire mass is developed from it, i.e. complete emptying of this hopper (the current source material at this time is loaded into hopper N2);

- set the width of the discharge gap of the crusher with a size of at least 2.5 diameters of the maximum piece of the source material;

- regulate the speed of unloading of crushed material from the crusher by means of a locking device, for example, in the form of a drum installed with the possibility of changing the speed of rotation;

- set the sieve with a given cell size on the screen;

- feed material from the hopper N1 to the crusher, and crushed from it to the screen;

- the over-screening product of the screen is sent to the same hopper N1, thus closing the crushing (grinding) cycle of the over-screening product, until almost the entire mass of less solid particles passes into the under-screening product;

- Oversize product with concentrated in it to a given diamond content is sent to a separate container for concentrate;

- the undersize product is disposed of and replaced by the functions of the hoppers N1 and N2.

When crushing relatively large classes (for example, 10-25 mm), the crusher discharge gap is set to at least 63 mm. In order to increase the productivity of the crusher, the crushed product is sent to a two-sieve screen with a mesh size of the upper sieve of 10 mm and the lower one, for example, 0.5 mm (justifying the size of the dump class). An intermediate class of 0.5-10 mm is sent for processing according to this method to another crusher with a discharge slot of at least 25 mm, operating in a closed cycle with a two-screen screen with a mesh size of sieves, for example 5 and 0.5 mm. In a crusher with a discharge gap width of 2.5 or more diameters of the maximum piece of the starting material and an adjustable rate of discharge of the crushed from the crusher by means of a locking device, for example, according to the method specified in the patent, the pieces of ore destroy each other, i.e. self-grinding is underway. In one stage of crushing, the weakest minerals pass into smaller classes, including the pulverulent fraction.

Example 1. It was experimentally established that with a width of the discharge gap of a jaw crusher, for example, 12.5 mm, and a particle size of 5–1 mm of the starting material, into an under-sieve screen product with a mesh size of 1 × 1 mm at various speeds of unloading from the working chamber in one the crushing stage takes from 20 to 35% of the crushed material. In this order, the mass of the circulating oversize product is reduced with each crushing cycle and, thus, the concentration of crystals in it increases from 1/50000000 to 1/5, i.e. 20%. Further concentration of diamonds is unsafe for crystal integrity. With their greater content in the working area of the crusher, the destruction of the crystals of themselves is possible. The figure 1/50000000 corresponds to approximately the average diamond content in kimberlite pipes. The 35% figure is due to the fact that with a further increase in the output of the under-sieve product during one crushing stage by reducing the speed of the material through the crusher, the productivity of the crusher for the newly formed under-sieve product is significantly reduced, since an increase in the content of small particles in the crusher working area worsens the fracture condition for larger ones. Therefore, the operation of the crusher in a closed cycle with a roar allows not only to isolate relatively solid particles, but also to increase the productivity of the crusher for the under-sieve product, all other things being equal.

The mesh size of the upper sieve during crushing of a pre-classified material is set equal to the lower limit of fineness of the starting material. The mesh size of the lower sieve is determined by the technical and economic analysis of ore preparation options, the content and cost of crystals, the size of which is less than the mesh sieve.

When crushing the source of unclassified material, the cell size of the upper sieve is determined by a technical and economic comparison of the options.

The advantages of the associated extraction of diamonds in the process of ore preparation according to the proposed method is that the relatively sophisticated diamond processing technologies are not based on such stable distinguishing features (liminescence, contact angle, etc.) as their hardness, with the same need to open the crystals by crushing and grinding of all ore to a certain size, the method allows to increase the concentration of diamond crystals from 1/50000000 to 1/5, i.e. by 20%.

Claims (1)

A method for concentrating diamonds at the ore preparation stage, comprising crushing diamond-containing material in a crushing crusher with an unloading slot of at least 2.5 diameters of the maximum initial piece, equipped with a locking device installed with the ability to control the discharge speed of the crushed material from the crusher, characterized in that they stop feeding to the bunker of the source material until the entire mass is completely developed from it, the crushed product is fed to a screen, providing passage from 20 to 35% of the crushed material rial for one stage of crushing at various speeds of unloading from the crusher, while the oversize product is sent to the hopper and then again to the crusher, forming a circulation of the crushed oversize product in a closed cycle with a roar to the required concentration of diamonds in it.