Correct use of flotation reagents

How to correctly use flotation reagents is the problem of how to correctly determine the reagent system before flotation. The reagent system refers to the type, dosage, mode, place and sequence of reagents added in the flotation process. The reagent system of flotation plant is related to the properties of ore, technological process and the need to obtain several mineral processing products. Ore is usually determined by beneficiability test or semi-industrial test. The reagent system is an important factor affecting the technical and economic indicators of mineral processing.

1. Kinds of Pharmaceuticals

The types of medication used in flotation plants are related to the properties of ores, technological process and the need to obtain several mineral processing products. Ore is usually determined by beneficiability test or semi-industrial test.

Pharmaceuticals can be classified into three categories according to their functions.

(1) Foaming agent: Organic surfactant distributed on water-air interface. It is used to produce foam layer which can float mineral. The foaming agent is pine oil, cresol oil, alcohol and so on.

(2) Collector: Its function is to collect the target minerals. Collector can change the hydrophobicity of mineral surface and make the floating mineral particles adhere to the bubbles. According to the properties of the agents, they can be divided into non-polar collectors, anionic collectors and cationic collectors. The commonly used collectors are black medicine, xanthate, white medicine, fatty acid, aliphatic amine, mineral oil and so on.

(3) Regulators: Regulators include activators and inhibitors, which change the surface properties of mineral particles and affect the role of minerals and collectors. Regulators are also used to change the chemical or electrochemical properties of water media, such as changing the pH value and the state of collectors. The adjusting agents include: (1) pH adjusting agents: lime, sodium carbonate, sulfuric acid, sulfur dioxide; (2) activating agents: copper sulfate and sodium sulfide; (3) inhibitors: lime, yellow blood salt, sodium sulfide, sulfur dioxide, sodium cyanide, zinc sulfate, potassium dichromate, sodium silicate, tannin, soluble gum, starch, synthetic polymer, etc. (4) Others: wetting agent, flotation agent, solubilizer, etc.

2. Drug dosage:

When flotation, the dosage of reagent should be appropriate. Insufficient or excessive dosage will affect the beneficiation index, and excessive dosage will increase the cost of beneficiation.

The relationship between the dosage of various reagents and flotation index

The inadequate dosage of collector and the insufficient hydrophobicity of mineral make the recovery rate decrease, the excessive dosage of collector make the quality of concentrate decrease, and bring difficulties to separation and flotation.

The amount of frothing agent is insufficient, the foam stability is bad, and the dosage is too large.

The selectivity of flotation process will be destroyed if the dosage of activator is too small, the activation is not good and the dosage is too large.

Inadequate dosage of depressant, low grade of concentrate and excessive dosage of depressant will restrain the minerals that should be floated and reduce the recovery rate.

3. Disposition of reagents

 Dilution of solid reagents into liquid, easy to add. Drugs with poor water solubility, such as xanthate, amine black powder, sodium silicate, sodium carbonate, copper sulfate, sodium sulfide and so on, were added into the aqueous solution, and the concentration of the preparation varied from 2% to 10%. Water-insoluble medicines should be dissolved in solvents first, and then mixed into aqueous solutions to add, such as amine collectors, some can be added directly, such as 2 # oil, 31 black medicine, oleic acid, etc. For water-soluble drugs with high dosage, the concentration of formulation is usually 10-20%, such as sodium sulfide 15% when used. For water-insoluble agents, organic solvents can be used to dissolve them, and then a low concentration solution can be prepared.

The selection of preparation methods of medicines mainly depends on the properties, adding methods and functions of medicines. The dosage and effect of the same medicament vary greatly due to different preparation methods. Generally, the preparation methods are as follows:

(1) When 2%-10% aqueous solution is prepared, most of the water-soluble medicines are prepared in this way (such as xanthate, copper sulfate, sodium silicate, etc.).

(2) Solvent preparation, some insoluble in water, can dissolve in special solvents, for example, Baiyao insoluble in water, but soluble in 10%-20% aniline solution, mixed with aniline solution before use; For example, aniline black medicine insoluble in water, but soluble in sodium hydroxide alkaline solution, so that When using aniline black medicine, the basic solution of sodium hydroxide should be prepared first, and then the aniline black medicine solution should be added to the flotation machine.

(3) The suspension or emulsion can be prepared for the use of some insoluble solid agents. If the solubility of lime in water is very small, the lime can be ground into powder and water can be mixed into emulsion suspension (e.g. lime milk), or directly into ball mill and mixing barrel with dry powder.

(4) Saponification is the most common method for fatty acid collectors, such as the use of oxidized paraffin soap and tar oil as collectors in hematite separation. In order to saponify the tar oil, about 10% sodium carbonate was added to the pharmaceutical preparation, and the hot soap solution was added by heating.

(5)Emulsification, emulsification method is to use ultrasonic emulsification, or mechanical strong stirring for emulsification. For example, after emulsification, fatty acids and diesel oil can increase their dispersion in pulp and improve the effect of the reagent. Adding part of emulsifier is more effective. Many surface active substances can be used as emulsifiers.

(6)Acidification, when using cationic collector, because of its poor solubility, it must be treated with hydrochloric acid or acetic acid before it can be dissolved in water for flotation.

(7)Aerosol method is a new preparation method to strengthen the effect of reagents. Its essence is to use a special spray device to atomize reagents in air medium and add them directly to the flotation tank, so it is also called "aerosol flotation method". This method not only improves the floatability of useful minerals, but also reduces the dosage of reagents. For example, the collector is only 1/3-1/4 of the usual dosage, while the foaming agent is only 1/5.

(8)The electrochemical treatment of flotation reagent in solution by direct current can change the state of the reagent itself, the pH value of the solution and the redox potential value, so as to increase the concentration of the most active reagent components, the critical concentration of forming colloidal particles and the insoluble reagent in water. The purpose of dispersion degree etc.

Generally, collectors and foaming agents can be stirred for 1-2 minutes, while some agents need to be stirred for a long time, such as copper-lead separation using potassium dichromate to inhibit lead.

4. In order to give full play to the effect of flotation reagents, the general way of adding reagents is to add adjusting agents, inhibitors and some collectors (such as kerosene) to the ball mill in order to create an appropriate flotation environment as soon as possible. Collectors and foaming agents are often added to the first stirring tank of flotation. If there are two stirring barrels in flotation operation, activator should be added in the first stirring barrel and collector and foaming agent should be added in the second stirring barrel. According to the different roles of reagents in flotation machines, the adding sites are also different. For example, copper sulfate, xanthate and terpineol are added to the center of the first stirring tank, xanthate is added to the center of the second stirring tank, and terpineol is added to the outlet of the second stirring tank. In general, flotation plants add pH adjusting agent first and adjust the pulp to a suitable pH value in order to better play the role of collectors and inhibitors. Attention should be paid to the problem of drug failure caused by some harmful ions when adding medicines. For example, the reaction between copper ion and hydride ion will make the hydride ineffective. If there are more copper ions in the stirred tank when separating copper from sulfur, cyanide should not be added to the stirred tank, but should be added directly to the separation flotation operation.

5. Drug-adding sequence: The general order of drug-adding in flotation plant is: the flotation of raw ore should be pH adjusting agent, depressant or activator, foaming agent, collector, and the minerals inhibited by flotation are activator, collector and foaming agent.

6. Drug-adding methods: There are usually two kinds of drug-adding: centralized and dispersed. The general principle is: for soluble in water, not easy to be taken away by foam, not easy to lose efficacy agents can be added centrally, that is, before rough selection, all agents can be added centrally at one time. On the contrary, for those medicines which are easily taken away by foam and easily invalidated by interaction with fine mud and soluble salts, they should be added in stages. Regulators, inhibitors and some collectors (e.g. kerosene) are added to the ball mill. Collectors and foaming agents are mostly added to the first stirring barrel of flotation. If there are two stirring barrels in flotation operation, activators should be added to the first stirring barrel and collectors and foaming agents should be added to the second stirring barrel (e.g. zinc flotation operation).

In order to improve the efficiency and save the dosage of medicines, many experimental studies have been carried out in recent years at home and abroad on the application of physical methods to enhance the efficacy of medicines. Among them, emulsification, heating flotation, aerosol method, treatment of electric field and magnetic field, use of ultraviolet radiation, use of high-energy radiation to strengthen the flotation process and the role of reagents, etc.