Flotation regulator overview

Flotation regulator overview

1 Overview

In addition to the collector and foaming agent, the flotation regulator includes various chemicals used in the flotation process. According to the role of the regulator in the flotation process, it can be divided into: pH adjuster, dispersant , inhibitors, activators, coagulants and flocculants. In fact, the modifier involves almost all kinds of inorganic compounds, organic compounds, and polymer compounds. Because the same flotation regulator can play different roles under different flotation conditions, the classification of the modifier has a certain degree of relativity. For example, lime is a pH adjusting agent, is also an agent, or pyrite aggregation inhibitors; different amounts of sodium sulfide slightly oxidized surface of the copper ore yellow activation or inhibition will play two distinct roles; many inhibitors such as water glass and sodium hexametaphosphate phosphate also has dispersant action.

2. pH値 adjuster

2. 1 Acidity regulator

The acidity adjusting agent mainly includes sulfuric acid, hydrochloric acid, phosphoric acid and hydrofluoric acid, and further includes carbon dioxide and sulfur dioxide or sulfurous acid. Nitric acid has strong oxidizing properties and is highly corrosive, and is generally not used as a flotation pH adjuster.

A sulfuric acid

Sulfuric acid is the most widely used industrial acid and the cheapest acid regulator. Sulfuric acid is a colorless, odorless oily liquid with a 98% concentrated sulfuric acid density of 1.84 g/cm3, which is highly corrosive. Sulfuric acid is inexpensive and non-volatile. It is the most widely used acid regulator in flotation. It is generally used in 10% to 20% mass concentration.

B hydrochloric acid

Hydrochloric acid is also a strong acid, and industrial hydrochloric acid generally has a mass concentration of about 30%. Hydrochloric acid has high volatility, high corrosivity, high transportation cost, and less application in flotation. However, in the flotation of certain minerals, such as the flotation of sodium chloride and potassium chloride, hydrochloric acid is required as an acid regulator. In addition, if you have a rich source of hydrochloric acid by-products, you can also consider using it.

C hydrofluoric acid

Hydrofluoric acid is expensive and highly toxic and highly corrosive, special attention should be used, is generally only used when some rare metal mineral flotation.

D phosphoric acid

Is a phosphate tribasic acid, its price is more expensive, as the pH adjusting agent is mainly used for the flotation of phosphate rock, in the use of larger amounts of phosphate rock phosphate magnesium reverse flotation off.

E sulfurous acid and carbonic acid

The hydrates formed by the dissolution of sulfur dioxide and carbon dioxide in water are referred to as sulfurous acid and carbonic acid, respectively. Sulfuric acid is a binary medium strong acid and carbonic acid is a binary weak acid. Some beneficiation plant pulp with carbon dioxide or sulfur dioxide slurried exhaust gases, substantially play the role of addition of carbonate and sulfite, may lower the pH.

2. 2 alkaline regulator

Alkaline modifiers commonly used in the flotation industry are lime, sodium carbonate and sodium hydroxide.

A lime

Calcium is inexpensive and has a wide range of sources. It is the most widely used alkaline regulator in flotation. Lime is a white solid with the main component being calcium oxide. Lime is not only an alkaline pH adjuster, but also has a strong inhibitory effect on sulfide minerals such as pyrite and pyrrhotite. Therefore, the application of lime in sulfide ore flotation is very common. Industrial lime is solid, easy to absorb moisture, and contains a certain amount of slag. Therefore, the concentrator generally uses lime to prepare lime milk for use.

B sodium carbonate

Sodium carbonate, also known as soda, is second only to lime in the flotation industry and is widely used in non-sulfide ore flotation. Sodium carbonate is a weak acid and strong alkali salt, which is ionized and hydrolyzed in water and is alkaline.

Sodium carbonate solution is not only alkaline, but also has two weak acid radicals with different acidity to form a buffer solution. Therefore, sodium carbonate also has a certain buffering effect, and the pH of the slurry is usually kept at 8-10.

Since fatty acid collectors are sensitive to calcium and magnesium ions, it is not advisable to use lime as a pH adjuster. In the flotation of various non-sulfurized ores, sodium carbonate can not only adjust the pH value, but also precipitate calcium ions and magnesium ions in the slurry, eliminate harmful effects and improve the selectivity of the flotation process.

In the sulphide ore flotation, sodium carbonate activates the lime-reduced pyrite. The carbonate ions and hydrogencarbonate ions dissociated from sodium carbonate can react with the hydrophilic film of iron hydroxide or calcium hydroxide on the surface of the pyrite to form the corresponding iron and calcium carbonate, due to the carbonate and Pyrite is different in nature and easily detaches, thereby activating pyrite.

C sodium hydroxide

Sodium hydroxide, commonly known as caustic soda, caustic soda, caustic soda. Pure sodium hydroxide is a white solid, very soluble in water. It releases a lot of heat when dissolved. It is easy to deliquesce. The aqueous solution has astringent and slippery feel and is highly corrosive. Sodium hydroxide is more alkaline than lime, but it is more expensive. Generally, sodium hydroxide is used under the condition that strong alkaline pulp is required and lime cannot be used. For example, in the process of selecting flocculation-de-soda-cation reverse flotation gangue in foreign hematite, in order to fully disperse the fine-grained mineral components, the required strong alkaline medium conditions require the use of sodium hydroxide. In addition, sodium hydroxide can also be used in combination with water glass or the like to enhance the dispersion of fine minerals.

3 dispersant

3. 1 role of dispersant

In the flotation process, the dispersant is often used in combination with a regulator such as a collector, a flocculant, an activator, or an inhibitor. The dispersing agent can make the ore particles in the slurry in a stable dispersion state, so that the collector or the flocculating agent can be selectively adsorbed on the surface of the target mineral particles to achieve the purpose of sorting.

The basic premise of mineral flotation separation is that the mineral particles have to reach the monomer dissociation state. Although the grinding can make the minerals reach the requirement of monomer dissociation, in the actual pulp, due to the complex mineral composition, the particle size distribution is wide, and the pulp contains many impurity metal ions, and the mineral particles aggregate to form mutual condensation. phenomenon. Co-coagulation is a non-selective agglomeration that produces a slime cover that results in non-selective flotation and a significant deterioration in the flotation process.

The role of the dispersant is to eliminate the phenomenon of mutual condensation and to keep the ore particles in a stable dispersion state. According to the DLV0 theory, the stability of the solid-liquid dispersion system depends on the balance between the repulsive force and the gravitational force between the particles. To make the solid particles uniformly disperse, the repulsive force between the particles must overcome the gravitational force, and conversely, coagulation or flocculation occurs. The repulsion between particles depends mainly on their electrostatic repulsion and surface hydration.

The dispersant includes an inorganic dispersant and an organic dispersant. The inorganic dispersing agent mainly includes water glass, sodium hydroxide, sodium carbonate, sodium hexametaphosphate, etc.; the organic dispersing agent is mainly an organic polymer having a small molecular weight, such as tannin, calcium lignosulfonate and the like. Dispersants usually also have the effect of inhibitors, especially organic dispersants tend to significantly affect the floatability of minerals, and their inhibition is more prominent, so they are mainly classified as organic inhibitors. At present, the dispersant used in the flotation process is mainly an inorganic dispersant, and the most widely used ones are water glass and sodium hexametaphosphate.

4 inhibitor

4. 1 The role of inhibitors

Inhibitors generally refer to flotation agents that inhibit the flotation of minerals. The so-called inhibition refers to enhancing the hydrophilicity of minerals, hindering or impairing the adsorption of minerals by collectors, thereby reducing the floatability of minerals. Inhibitors are usually used in combination with collectors. In general, a good inhibitor should not affect the adsorption and collection of the collector on the target mineral surface, but it can hinder or weaken the collector in other minerals. The role of the surface, thereby increasing the selectivity of flotation separation. At the same time, the inhibitor should also have a wide range of sources, low cost, non-toxic or low toxicity, and easy to use. Different collectors and different mineral systems often require different inhibitors. Therefore, among the flotation agents, the types of inhibitors are the largest and the amount of use is also the largest.

Inhibitors typically include two major classes of inorganic and organic inhibitors. Among them, organic inhibitors can be further classified into small molecule organic inhibitors and macromolecular organic inhibitors according to their relative molecular weights.

4. 2 inorganic preparations

There are many types of inorganic inhibitors. The aforementioned pH adjusters and dispersants are also inhibitors. For example, lime is an inhibitor of pyrite, and it is sulfided in copper-sulfur, copper- zinc -sulfur and lead -zinc-sulfur. It is widely used in the selection; water glass and sodium hexametaphosphate are also high-efficiency inhibitors of gangue minerals such as quartz and silicate, and are widely used in oxidized ore flotation.

4.3 small molecule organic inhibitors

Small molecule organic inhibitors generally have a hydrophilic group, which is linked to another hydrophilic group capable of inhibiting mineral action by a target. This structure enhances the hydrophilic group after the action of minerals and inhibitors, and it is difficult to produce sulfur hydration. Thereby inhibiting the mineral floating. The carboxylic acid group, the amino group and the hydrocarbon group are all strong hydrophilic groups, and the inhibitor formed mainly includes a hydroxycarboxylic acid, a hydroxylamine, a dicarboxylic acid, a glycol, and the like. Small molecule organic inhibitors include: carboxylic acids, amines, alcohol inhibitors, thioacid salts, thioglycolic acid (salt), mercaptoethanol, aryl sulfonic acid, and the like.

4. 4 macromolecular organic preparations

Macromolecular organic inhibitors generally refer to polymeric compounds, including natural polymers and synthetic polymers. The polymer compound is not only used as an inhibitor in the flotation, but is also widely used as a flocculant due to flocculation. Macromolecular organic preparations mainly include: starch and its derivatives, carboxymethyl cellulose, lignosulfonate, humic acid and the like.

5 activator

5. 1 Acting agent

Activation refers to the ability to promote and enhance the interaction of minerals with collectors to increase the floatability of minerals, and agents that can do this are called activators.

According to the chemical nature of the activator, the active agent can be classified into metal ion activators, inorganic acids, inorganic bases, sulfides, organic activators and the like.

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