Heavy medium beneficiation principle and common equipment

       1. What is the principle of heavy medium mineral processing ? This method mainly determines what factors in the ore?

Heavy medium beneficiation is the process in which the ore group is separated by specific gravity in a medium with a specific gravity greater than water. The specific gravity of the heavy medium is between the small specific gravity mineral and the large specific gravity mineral, and the mineral with a small specific gravity floats therein, sinking more than the major mineral, and respectively discharging different products.

This method of selection is mainly determined by the specific gravity of the ore particles, and the influence of the particle size and shape of the ore particles is small, so the classification accuracy is high and high, and the minerals with small difference in specific gravity (such as 0.1) can be selected; The granularity range can be wide and the processing capacity is large.

2. What are the application conditions for heavy media beneficiation? What are the advantages?

The application conditions for heavy medium beneficiation are that the ore particles to be sorted must have a suitable lower particle size limit and an upper particle size limit.

Since the ore particles with a small particle size, especially the specific gravity of the ore particles, are close to the specific gravity of the heavy medium, the sedimentation speed of the ore particles is small, so the separation process is slow and the sorting efficiency is greatly reduced. Therefore, in industrial production, in order to ensure the faster separation and higher accuracy of the separation of the ore particles, the lower limit of the particle size is limited, that is, the particle size cannot be too small. Therefore, the fine fraction is often screened out before the heavy medium is selected. Currently metal ore particle size limit in the use of dense medium separation is typically 2-3 mm, if using heavy medium cyclone, the lower limit of the particle size can be reduced to 0.5 mm.

The upper limit of the particle size is selected based on the equipment conditions and the characteristics of the ore. For metal beneficiation, it is generally 70-100 mm. At present, heavy medium beneficiation is commonly used to treat ore with coarse grain inlays or aggregate inlays.

The use of heavy medium beneficiation can remove a large amount of monomeric gangue, so that the amount of ore entering the next process is greatly reduced, thereby improving the production capacity of the concentrator and saving the ore dressing cost. Since heavy medium beneficiation has such advantages, this beneficiation method is commonly used as a pre-selection operation in metal ore dressing plants.

3. What are the types and composition characteristics of heavy medium dressing media?

There are two main types of media for heavy media beneficiation: 1) heavy liquid; 2) heavy suspension.

The heavy liquid is a homogeneous liquid in which an aqueous solution of a high specific gravity inorganic salt and a high specific gravity organic liquid are present. The tribromo methane (CHBr3), tetrabromoethane (C2H2Br4) and the organic solution composition. Proportion of up to 2.9-3.0; mercuric iodide and potassium iodide (KI + HgI2) aqueous solution, up to a specific gravity 3.17-3.2 but limited sources of heavy and expensive solution, there are also toxic, and easy sorting viscosity. The product is separated, etc., so it is rarely used in industrial production.

A resuspension is a heterogeneous medium composed of a mixture of high specific gravity solid particles (generally referred to as suspended matter) and water (or air). Most of the suspended particle size of less than 0.074 mm, the suspended materials commonly used are: pyrite, magnetite, galena, ferrosilicon. As a raw material for suspension, it has a wide range of sources, is inexpensive, non-corrosive, and easy to recycle. It has been widely used in industrial production.

4. What are the factors that affect the effect of heavy media beneficiation?

The factors affecting the effect of heavy medium selection are mainly the nature of the suspension. In particular, the specific gravity, viscosity and stability of the suspension. The specific gravity of the suspension increases with the increase of the volume concentration of the suspended matter. When the volume concentration increases, the viscosity of the suspension also increases gradually, which will increase the movement resistance of the ore particles, thereby making the sorting accuracy. And equipment productivity is reduced. The smaller the ore particle size, the lower the viscosity of the required suspension should be, in order to facilitate the rapid and accurate sorting of the ore. Therefore, the concentration of the suspension should have a suitable range.

It is also important to maintain the stability of the suspension, so stability is the key to keeping its specific gravity constant. Since the suspended particles are subjected to their own gravity, the specific gravity of the suspension changes when the sedimentation occurs, the upper layer becomes smaller, and the lower layer becomes larger, which affects the normal operation of the selection process. In order to prevent the sedimentation of suspended solids during production, mechanical agitation, vibration, and the use of rising or horizontal water flow and the addition of suitable stabilizers are often used.

5. What are the commonly used equipment for heavy media ore dressing?

Commonly used equipment for heavy medium dressing are: cone cone sorting machine, cylinder sorting machine, heavy medium vibration chute and heavy medium cyclone.

6. What is the solid volume concentration of heavy medium suspension? How much is the usual concentration?

The volumetric concentration of the suspension solids, ie the volume of suspended matter in the suspension, is a percentage of the total volume of the suspension.

Calculation formula: solid volume concentration = (volume of suspended matter in suspension / volume of suspension) × 100%

The volume concentration of the suspension of the commonly used heavy medium concentrator is generally controlled below 35%. However, in the process of selecting the heavy medium chute, the fine-grained magnetite with low specific gravity is used as the suspended matter, so when the volume concentration is 55-60%, the selection process can still proceed smoothly.

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