The problem of how to use the flotation reagent correctly, that is, how to correctly determine the reagent system before flotation. The reagent system refers to the type of reagent added in the flotation process, the dosage of the reagent, the method of addition, the place of addition and the order of addition, etc., the reagent system of the flotation plant is related to the nature of the ore, the process, the need to obtain several mineral processing products and other factors. It is usually determined by ore washability test or semi-industrial test. The reagent system is an important factor affecting the technical and economic indicators of mineral processing.
1. Type of medicament
The types of drugs used in the flotation plant are related to the nature of the ore, the process flow, and the need to obtain several mineral processing products. It is usually determined by ore washability test or semi-industrial test. The types of drugs are divided according to the role of drugs, which can be roughly divided into three categories.
(1) Foaming agent: an organic surface active substance distributed on the water-air interface. It is used to produce a foam layer capable of floating minerals. The foaming agent includes pine oil, cresol oil, alcohols, etc;
⑵ Collector: Its function is to collect the target mineral. The collector can change the hydrophobicity of the mineral surface and make the floating mineral particles adhere to the bubble. According to the nature of the action of the reagent, it is divided into non-polar collectors, anionic collectors and cationic collectors. The commonly used collectors are black medicine, xanthate, white medicine, fatty acid, fatty amine, mineral oil, etc;
(3) Adjusting agents: Adjusting agents include activators and inhibitors, which change the properties of the surface of ore particles and affect the action of minerals and collectors. Adjusting agents are also used to change the chemical or electrochemical properties of aqueous media, for example, to change the pH value and the state of collectors. Adjustors are:
① pH regulator: lime, sodium carbonate, sulfuric acid, sulfur dioxide;
② Activator: copper sulfate, sodium sulfide;
③ Inhibitors: lime, yellow blood salt, sodium sulfide, sulfur dioxide, sodium cyanide, zinc sulfate, potassium dichromate, water glass, tannin, soluble colloid, starch, synthetic polymer, etc;
④ Others: wetting agent, floating agent, solubilizer, etc.
2. Dosage of medicament
The dosage of flotation reagent should be just right, insufficient or excessive dosage will have an impact on the mineral processing index, and excessive dosage will increase the cost of mineral processing. The relationship between the dosage of various reagents and the flotation index is:
(1) The amount of collector is insufficient, the mineral hydrophobicity is not enough, so that the recovery rate is reduced, the amount of drug is too large, the concentrate quality is reduced, and the separation flotation is difficult;
⑵ The amount of foaming agent is insufficient, the foam stability is poor, the amount is too large, and the phenomenon of "running groove" occurs;
(3) If the dosage of activator is too small, the activation is not good, and the dosage is too large, it will destroy the selectivity of the flotation process;
(4) Insufficient dosage of inhibitor, low grade of concentrate, and excessive dosage of agent will inhibit the minerals that should be surfaced and reduce the recovery rate.
3. Drug configuration
Dilute the solid agent into a liquid for easy addition. Poor water-soluble drugs such as xanthate, amine black medicine, water glass, sodium carbonate, copper sulfate, sodium sulfide, etc. are prepared into aqueous solution to add, the preparation concentration of 2% to 10%. Insoluble in water to the first solvent dissolved, and then prepared into an aqueous solution to add, such as amine collector, some can be directly added such as 2# oil, No. 31 black medicine, oleic acid and so on. For easily soluble in water and a large amount of pharmaceutical preparation concentration is generally 10 ~ 20%, such as sodium sulfide in the use of the preparation of 15%. In the case of a drug which is hardly soluble in water, it can be dissolved with the aid of an organic solvent and then prepared into a low-concentration solution.
The selection of the preparation method of the medicament is mainly based on the nature, addition method and function of the medicament. The same kind of medicine, due to the different preparation methods, the dosage and effect are very different, the general preparation methods are:
① formulated into a 2% to 10% aqueous solution, most of the water-soluble agents are so prepared (such as xanthate, copper sulfate, water glass, etc.);
② preparation by adding solvent, some drugs insoluble in water can be dissolved in special solvents. for example, baiyao is insoluble in water, but soluble in 10% ~ 20% aniline solution, which can only be used after preparing aniline mixed solution. Another example is that aniline black drug is insoluble in water but soluble in alkaline solution of sodium hydroxide, so when using aniline black drug, the alkaline solution of sodium hydroxide should be prepared first, then adding the agent to prepare an aniline black drug solution and adding it to the flotation agent;
③ formulated into suspension or emulsion, for some insoluble solid pharmaceutical, can be formulated into emulsion use. If the solubility of lime in water is very small, the lime can be milled into powder and mixed with water into a milky suspension (e. g. milk of lime), or it can be directly added to the ball mill and stirring barrel in the form of dry powder;
④ saponification, for fatty acid collectors, saponification is the most common method, such as the selection of hematite, with oxidized paraffin soap and tar oil with the use of as a collector. In order to saponify the tar oil, about 10% sodium carbonate is added when preparing the reagent, and heated to make a hot soap solution to add;
The emulsification, emulsification method is the use of ultrasonic emulsification, or the use of mechanical stirring for emulsification. Such as fatty acids and diesel after emulsification, can increase their dispersion in the pulp, improve the effect of the role of the agent. Add part of the emulsifier agent effect is better. Many surface-activated substances can be used as emulsifiers;
The acidification, in the use of cationic collector, because of its poor solubility, it must be treated with hydrochloric acid or acetic acid, and then can be dissolved in water for flotation;
The aerosol method is a new preparation method to strengthen the role of the agent. Its essence is to use a special spray device to atomize the agent in the air medium and then directly add it to the flotation tank, so it is also called "aerosol flotation method". The use of this method not only improves the floatability of useful minerals, but also significantly reduces the amount of pharmaceutical agents. For example, the collector is only 1/3~1/4 of the usual amount, while the amount of foaming agent is only 1/5;
⑧ The electrochemical treatment of the reagent, in the solution, the chemical treatment of the flotation reagent 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 improve the concentration of the most active reagent component, improve the critical concentration of the formation of colloidal particles and improve the dispersion degree of the insoluble reagent in water. Usually collector, foaming agent can be stirred for 1-2 minutes, and some agents need to be stirred for a long time, such as potassium dichromate for copper-lead separation to inhibit lead.
4. Dosing location
In order to give full play to the effect of flotation reagents, the general practice of dosing sites is: regulator, inhibitor and part of the collector (such as kerosene) added to the ball mill in order to create a suitable flotation environment as soon as possible. Collector and frother are added in the first mixing tank of flotation.
If the flotation operation has two mixing tanks, the activator should be added to the first mixing tank, and the collector and frother should be added to the second mixing tank. Depending on the role of the agent in the flotation machine, the addition site is also different.
For example, copper sulfate, xanthate and pine alcohol oil are added to the center of the first stirred tank, xanthate is added to the center of the second stirred tank, and pine alcohol oil is added to the outlet of the second stirred tank. Flotation plant in general, first add pH regulator, the pulp adjusted to a suitable pH value in order to better play the role of collectors and inhibitors. When adding the medicament, pay attention to the problem that certain harmful ions cause the medicament to fail.
For example, the reaction of copper ions and hydride ions will cause the hydride to fail. When copper and sulfur are separated, if there are more copper ions in the stirred tank, cyanide should not be added to the stirred tank, but should be directly added to the separation flotation operation.
5. Dosing sequence
The general dosing sequence of flotation plant is: for the flotation of raw ore, it should be: pH value regulator, inhibitor or activator, foaming agent, collector,; The minerals that have been suppressed in flotation are: activator, collector and foaming agent.
6. Dosing Method
There are usually two kinds of centralized addition and decentralized addition. The general principle is: for easily soluble in water, it is not easy to be taken away by foam, and drugs that are not easy to fail can be added centrally, I .e. all drugs can be added at one time before rough selection. On the contrary, for those easy to be taken away by the foam, easy to work with fine mud and soluble salts and failure of the agent, should be added in sections.
Regulator, inhibitor and part of the collector (such as kerosene) added to the ball mill, the collector and frother added in the flotation first mixing tank, if the flotation operation has two mixing tanks, should be in the first mixing tank activator, the second mixing tank plus collector and frother (such as zinc flotation operations).
7. Summary
In order to improve the efficiency of the agent and save the dosage of the agent, in recent years, a lot of experimental research work has been carried out at home and abroad in the application of physical methods to strengthen the efficiency of the agent. Among them are emulsification, heating flotation, aerosol method, electric field and magnetic field treatment, the use of ultraviolet radiation, the use of high energy radiation to strengthen the flotation process and the role of reagents.