The issue of how to use flotation reagents correctly is the issue of how to correctly determine the medicament system before flotation. The medicament system refers to the type of reagents added during the flotation process, the amount of reagents, the method of addition, the location of dosing, the order of dosing, etc. The reagent system of the flotation plant is related to the nature of the ore, the process flow, the several mineral processing products that need to be obtained, and other factors. related. It is usually determined through optional testing of ores or semi-industrial testing. The pharmaceutical system is an important factor affecting the technical and economic indicators of mineral processing.
1. Types of pharmaceuticals
The types of chemicals used in flotation plants are related to factors such as the nature of the ore, the process flow, and the types of mineral processing products that need to be obtained. It is usually determined through optional tests or semi-industrial tests of ores. The types of pharmaceuticals are divided according to their functions and can be roughly divided into three categories.
● Foaming agent: organic surface-active substances distributed on the water-air interface. Used to produce a foam layer that can float minerals. Foaming agents include pine oil, cresol oil, alcohols, etc.;
● Collecting agent: Its function is to collect the target mineral. The collecting agent can change the hydrophobicity of the mineral surface and make the floating mineral particles adhere to the bubbles. According to the action properties of the agent, it is divided into non-polar collectors, anionic collectors and cationic collectors. Commonly used collectors include black medicine, xanthate, white medicine, fatty acids, fatty amines, mineral oil, etc.;
● Adjusters: Adjusters include activators and inhibitors, which change the properties of the surface of mineral particles and affect the interaction between minerals and collectors. Adjusters are also used to change the chemical or electrochemical properties of aqueous media, such as changing the pH value and The state of the collector. Adjusters include:
①. pH adjuster: 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 high molecular polymer, etc.;
④. Others: wetting agents, floating agents, solubilizers, etc.
2. Medication dosage
The dosage of reagents during flotation must be just right. Insufficient or excessive dosage will affect the mineral processing index, and excessive dosage will increase the cost of mineral processing. The relationship between the dosage of various chemicals and the flotation index is:
①. Insufficient dosage of collector and insufficient hydrophobicity of the minerals will reduce the recovery rate. Excessive dosage will reduce the quality of the concentrate and bring difficulties to separation and flotation;
②. Insufficient dosage of foaming agent will lead to poor foam stability, and excessive dosage will cause “groove running” phenomenon;
③. If the dosage of activator is too small, the activation will not be good, and if the dosage is too large, it will destroy the selectivity of the flotation process;
④. Insufficient dosage of inhibitors, low concentrate grade, and excessive dosage will inhibit the minerals that should emerge and reduce the recovery rate.
3. Pharmacy configuration
Dilute solid medicine into liquid for easy addition. Agents with poor water solubility, such as xanthate, amylanine, sodium silicate, sodium carbonate, copper sulfate, sodium sulfide, etc., are all prepared into aqueous solutions and added in concentrations ranging from 2% to 10%. Agents that are insoluble in water should be dissolved in a solvent first, and then added into an aqueous solution, such as amine collectors. Some can be added directly, such as #2 oil, #31 black powder, oleic acid, etc. For pharmaceuticals that are easily soluble in water and have a large dosage, the preparation concentration is generally 10 to 20%. For example, sodium sulfide is prepared at 15% when used. For pharmaceuticals that are poorly soluble in water, organic solvents can be used to dissolve them and then be prepared into low-concentration solutions.
The choice of pharmaceutical preparation method is mainly based on the properties, addition methods and functions of the pharmaceutical. The dosage and effect of the same medicine vary greatly due to different preparation methods. Generally, the preparation methods are as follows:
①. Prepare into a 2% to 10% aqueous solution. Most water-soluble pharmaceuticals are prepared in this way (such as xanthate, copper sulfate, water glass, etc.);
②. Prepare with solvent. Some water-insoluble pharmaceuticals can be dissolved in special solvents. For example, Baiyao is insoluble in water, but soluble in 10% to 20% aniline solution. After preparing the aniline mixed solution, can be used; for another example, aniline black drug is insoluble in water, but can be dissolved in the alkaline solution of sodium hydroxide, so when using aniline black drug, you must first prepare an alkaline solution of sodium hydroxide, and then add this agent to prepare Aniline black liquor solution is added to the flotation agent;
③. Formulate into a suspension or emulsion. For some solid pharmaceuticals that are not easily soluble, they can be formulated into an emulsion. If the solubility of lime in water is very small, the lime can be ground into powder and mixed with water to form a milky suspension (such as lime milk), or it can be added directly to the ball mill and mixing barrel in the form of dry powder;
④. Saponification. For fatty acid collectors, saponification is the most common method. For example, when selecting hematite, oxidized paraffin soap and Tarr oil are used together as collectors. In order to saponify tar oil, when preparing pharmaceuticals, add about 10% sodium carbonate and heat it to make a hot soap solution;
⑤. Emulsification. The emulsification method is to use ultrasonic emulsification or mechanical strong stirring for emulsification. For example, after emulsification of fatty acids and diesel oil, their dispersion in the slurry can be increased and the effect of the agent can be improved. Adding some emulsifiers will have better effects. Many surface-active substances can be used as emulsifiers;
⑥. Acidification. When using a cationic collector, due to its poor solubility, it must be pre-treated with hydrochloric acid or acetic acid before it can be dissolved in water and used for flotation;
⑦. The aerosol method is a new preparation method that enhances the effect of pharmaceuticals. Its essence is to use a special spray device to atomize the pharmaceuticals in the air medium and add them directly to the flotation tank. , so it is also called “aerosol flotation method”. Using this method not only improves the floatability of useful minerals, but also significantly reduces the dosage of chemicals. For example, the collector is only 1/3 to 1/4 of the usual dosage, and the foaming agent is only 1/5;
⑧. Electrochemical treatment of reagents. In the solution, direct current is applied to chemically treat the flotation reagents, which can change the state of the reagents themselves, the pH value of the solution and the redox potential value, thereby improving the most active pharmaceutical components. The purpose is to increase the critical concentration for forming colloidal particles and to improve the dispersion degree of poorly soluble agents in water. Usually collectors and foaming agents can be stirred for 1-2 minutes, but some agents require long-term stirring, 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 at the dosing location is to add regulators, inhibitors and some collectors (such as kerosene) into the ball mill to create a suitable flotation environment as early as possible. The collector and frother are added in the first stirring tank of flotation.
If the flotation operation has two mixing barrels, the activator should be added to the first mixing barrel, and the collector and frother should be added to the second mixing barrel. Depending on the role of the agent in the flotation machine, the adding location is also different.
For example, there are three chemicals: copper sulfate, xanthate, and pine alcohol oil. The general dosing sequence is to add copper sulfate to the center of the first stirring tank, xanthate to the center of the second stirring tank, and pine alcohol oil to the center of the second stirring tank. Exit. Under normal circumstances, flotation plants first add a pH adjuster to adjust the slurry to a suitable pH value in order to better exert the effects of collectors and inhibitors. When adding chemicals, be aware that some harmful ions may cause the medication to fail.
For example, the reaction between copper ions and hydride ions will cause the hydride to fail. During copper-sulfur separation, if more copper ions appear in the stirring tank, do not add cyanide to the stirring tank, but add it directly to the separation float. Selecting work.
5. Dosing sequence
The general order of dosing in a flotation plant is: for the flotation of raw ore, it should be: pH adjuster, inhibitor or activator, frother, collector; minerals whose flotation has been inhibited are: activator, Collector, foaming agent.
6. Dosing method
There are usually two types of centralized addition and dispersed addition. The general principle is: for agents that are easily soluble in water, difficult to be taken away by foam, and difficult to expire, they can be added together, that is, all agents can be added at once before rough selection. On the contrary, those agents that are easily carried away by the foam and are easily rendered ineffective by interacting with fine mud and soluble salts should be added in stages.
Adjusters, inhibitors and some collectors (such as kerosene) are added to the ball mill, and collectors and foaming agents are mostly added to the first mixing barrel of flotation. If there are two mixing barrels in the flotation operation, they should be added in the third mixing barrel. Add activator to one mixing barrel, and add collector and foaming agent to the second mixing barrel (such as zinc flotation operation).
Post time: Aug-20-2024
