Mineral processing common sense - flotation

Tianzhou Mining Company Expert Group Zheng Guangwei

Flotation is a wet sorting process in which the mined ore emerges from the suspension of water (pulp) according to the physicochemical properties of the mineral surface. At present, the foam flotation method is generally applied. The essence of the method is to grind the ore with water to form a slurry, add it to a flotation agent, then stir it in a flotation machine, and introduce air to form a bubble, so that a part of the floatable mineral adheres to the bubble, and The foam floats to the surface of the slurry to form a foam, which is a foam product, called a concentrate. Another part of the non-floating gangue, which cannot adhere to the bubbles and remains in the slurry, is often referred to as tailings. In this way, the purpose of separation is achieved. In short, the flotation process is the separation of useful minerals from the gangue in the ore.

First, flotation reagent

During flotation, flotation reagents play an important role in regulating the surface flotation properties of minerals, increasing flotation speed and selectivity.

Adjustable flotation reagent various minerals floatability, strengthening air dispersion in the pulp, increasing the stability of the foam, can also improve the properties of floating mineral slurry, in order to facilitate the flotation.

The flotation reagent can be classified into a collector , a foaming agent, a regulator, an inhibitor, an activator, etc., depending on its action.

Second, flotation machinery

The flotation machine should have the characteristics of reliable work, wear resistance, low power consumption, simple structure and convenient operation, just like ordinary machinery. In addition, the following special requirements should be met: aeration, agitation, slurry circulation, and all types of flotation machines must ensure maximum effective volume and flotation slurry level adjustment control during flotation.

The types of flotation machines can be divided into mechanical agitating and inflatable flotation machines according to their different inflation methods. Specific types include Mihanopur flotation machine, Waman flotation machine, and Beijing Mining Research Institute 8 cubic meters and other inflatable flotation machines.

Third, the flotation process

(1) Flotation principle process

Mainly solve the number of flotation process segments, that is, the number of segments of grinding. It can be one, two or more stages of grinding. The number of stages in the flotation process is mainly determined by the characteristics of the useful minerals in the ore and the muddy conditions during the grinding process.

A flotation process—a one-time grinding process—mills the ore directly to the desired particle size and then performs flotation. It is mainly suitable for ores with uniformly embedded minerals.

The secondary grinding process of the second stage flotation process is also called the stage flotation process. The main purpose of the stage flotation process is to avoid and prevent over-grinding and muddy of useful minerals.

(2) Priority flotation process

(3) Mixed flotation process:

(4) Flotation efficiency index

1. Grade: The weight fraction of the calculated weight per unit of raw material or product is expressed as a percentage (%). Usually, α, β, and ρ represent the original, refined, and tailing grades, respectively.

2. Yield: The product weight fraction of the raw ore is called the yield. Expressed as γ, the formula is (original grade minus tailing grade divided by concentrate grade minus tailing grade):

3. Recovery rate ε (expressed as ε%): The degree of recovery of valuable components in the ore during the beneficiation process, that is, the ratio of the content of valuable components in the product to the content of valuable components in the ore.

The theoretical recovery rate is calculated as:

4, enrichment ratio б:

The multiple of the refined grade to the grade of the original ore is called the enrichment ratio. Expressed as:

5. Dressing ratio (the ratio of tonnage of raw ore required for one ton of concentrate is called ore dressing ratio):

Represents the amount of concentrate and raw ore.

6, concentrate dehydration

In the flotation process, the concentrate contains a large amount of water, usually accounting for more than 70%. The concentrate needs to be removed before it is sent to smelting, otherwise it cannot be smelted. The moisture content of copper concentrate should not exceed 14% in summer, winter and less than 8%.

Concentrate dewatering is generally mechanical dehydration, the process is: dense filtration drying

The thick machinery has two types: central transmission type and peripheral transmission type thickener. Small and medium-sized concentrators use central-drive thickeners, and larger-scale concentrators use peripheral-driven thickeners.

Filtered machinery includes external filter, internal filter, disc vacuum filter and ceramic vacuum filter.

Drying operation: The product is usually dried by a direct heating kiln dryer. The advantages are high productivity, convenient operation and simple structure.

7. Tailings transportation and tailings storage

Abandoned tailings from various concentrators must be excluded. Due to the high yield of tailings, it usually accounts for more than 90% of the total processing capacity of the concentrator. Tailings contain a large number of various chemicals. If they are not properly handled, stored and accumulated, they will cause serious environmental pollution and even cause disasters. Therefore, tailings storage is an important part of the mineral processing process. The tailings treatment of the ore dressing includes: tailings transportation, tailings storage, tailings storage and accumulation, tailings storage and drainage facilities, tailings water purification and backwater utilization.

For tailings transportation, the tailings of the concentrator are generally delivered to the tailings pond with forced pressure. According to the elevation distance of the conveying, one section, two sections and even more sections are used for transportation. The equipment used is a sand pump.

8. Inspection and control of the production process

1Incoming raw materials (ore, chemicals and other consumables) and the varieties and quality standards of the products.

2 metering equipment is regularly checked;

3 Inspection and control of technical conditions of major equipment;

4 inspection of process operating conditions:

Inspection items: particle size analysis; slurry concentration; raw ore, dehydrated concentrate water determination; original, fine, tailings grade analysis; flotation slurry pH determination; drug dosage inspection and control.

(2) Inspection method

1 Determination of product moisture

2 Determination of the specific gravity of the slurry

among them:

P ₁ — empty pycnometer weight (g);

P ₂ — pycnometer + water weight (g);

P ₃ — pycnometer + pulp weight (g);

3 Determination of ore specific gravity (δ)

In the formula:

A — dry pycnometer + material weight (g);

B — empty bottle weight (g);

C — empty bottle weight + water weight (g);

D — Empty bottle + heavy water weight + material weight (g).

4 classifier overflow fineness rapid screening

In the formula:

r — the content of the sieve on the sieve level;

q — (concentration pot + sieve top + water) weight (g);

Q — Concentration pot + pulp weight (g);

V + P — weight after the empty pot is filled with water (g);

δ — the specific gravity of the ore.

(5) Theoretical calculation of classifier fineness

In the formula:

β - the calculated level content (%) in overflow or grit;

Y - concentration percentage (%) in overflow or grit;

a ——calculation level content (%) in the grader feeding (mine discharge);