1), inhibitor
Inhibitors are agents that reduce the floatability of minerals. The inhibition is varied and the corresponding agent should be selected depending on the performance of the agent.
Commonly used inhibitors are: chromium weight potassium (inhibition galena), zinc sulfate (inhibition sphalerite), lime (inhibition pyrite), cyanide (inhibiting sulfide ore), water glass (silicon inhibiting mineral salts ), sodium sulfide, and the like.
Lime ( CaO ) is an effective inhibitor of sulfide minerals such as pyrite and pyrrhotite. In the inhibition of pyrite, the formation of hydrophilic iron hydroxide thinner on the surface of the mineral increases the wettability of the surface of the pyrite and inhibits it. Lime has an effect on the foaming ability of the foaming agent. For example, the foaming ability of the pine oil oil foaming agent increases with the increase of the pH value, and the foaming ability of the phenolic foaming agent increases with the pH value. High and low.
Cyanide (NaCN or the KCN) is the most effective inhibitors of sulfide minerals in production practice, to inhibit multiple brass ore, sphalerite, pyrite. Cyanide is a salt formed by a strong base and weak acid, which can be hydrolyzed in the slurry. Therefore, the use of cyanide must maintain the alkalinity of the slurry. Cyanide is easily soluble in water and is usually added to a 1-2% aqueous solution when used.
Potassium dichromate ( Na2Cr2O7 ) content is above 99%, belonging to inorganic or inorganic substances, orange-red slanting line crystal, slightly soluble in water, soluble in hot water, acidic aqueous solution. It is an effective inhibitor of galena. Potassium dichromate is a strong oxidant in acidic media; the formation of chromic acid ions in weakly alkaline pulp oxidizes the surface of galena to PbSO4. The insoluble and hydrophilic PbCrO4 thin crucible is formed, thereby suppressing galena. In order to promote the inhibition of the potassium dichromate ore, the slurry requires a long time of stirring (30 min), and the pH of the slurry is maintained in the range of 7.4-8. When multiple metal sulfide ore flotation separation, potassium dichromate is mainly used to separate the mixed concentrate of copper and lead, lead inhibiting mineral, flotation of copper minerals. This is one of the most common methods of copper and lead separation.
The content of sodium sulfite (Na 2 SO 3 ) is 96% or more, white powder or small crystal, soluble in water, and the aqueous solution is alkaline. It is easily oxidized under humid and sunlight, has strong reducibility and cannot be stored and transported together with oxidant and strong acid.
Sulfur dioxide SO 2 is dissolved in water to form sulfurous acid. The solubility in water decreases with increasing temperature. At 18 ° C, it is absorbed by water, wherein the concentration of sulfurous acid is 1.2%. When the temperature is raised to 30 ° C, the concentration of sulfurous acid is reduced to 0.6%.
Sulfur dioxide and sulfite are mainly used to inhibit pyrite and sphalerite, and the general pulp pH is in the range of 5-7. Because of the timeliness of the suppression, in order to stabilize the process, a method of segmentation is usually adopted.
Zinc sulfate ( ZnSO4 ) is a colorless needle columnar crystal or white crystalline powder with a content of more than 92% and a zinc content of more than 20.91%. It is easily soluble in water and used in combination with alkali. It is an inhibitor of sphalerite. The mechanism of action is that the hydrophilic colloidal particles with OH-formed zinc hydroxide adsorb on the surface of the zinc blende, hindering the interaction between the mineral surface and the collector , and inhibiting the sphalerite. When zinc sulphate is used alone, its inhibitory effect is very poor, and it is usually used in combination with other inhibitors to obtain better effects.
Sodium sulfide ( Na2S ) is an inhibitor of most sulfide minerals. Its inhibition is that the sodium sulfide is hydrolyzed to form HS- or S2- ions, which can adsorb on the surface of the sulfide mineral and hinder the adsorption of the mineral on the collector anion, thereby inhibiting the mineral. In the practice of flotation, the role of sodium sulfide is multi-faceted. It can be used as an inhibitor of sulfide ore, an activator of non-ferrous metal oxide ore, a pH adjuster for pulp, and a decontamination of sulfide ore mixed concentrate.
Inhibitors such as sulfur dioxide (SO2) sulfurous acid (H2SO4) sodium sulfite (Na2SO3) and sodium thiosulfate (Na2S2O3) are also used in production, and often used in combination with other inhibitors, and good results are obtained.
The chemical name of water glass is sodium silicate ( Na2SIO4 ) , which is prepared by co-solubilizing alkali and quartz sand. The water glass formula is often expressed as: Na2O.MSIO2; (m is the "modulus" of sodium silicate, or sodium to sodium ratio). Water glass is an inhibitor of quartz, silicate gangue minerals and slime dispersant. . The inhibition of water glass is absorbed by the hydrated HSIO2-, SIO2- and silicic acid micelles on the surface of the mineral to form a hydrophilic thin crucible, thus weakening the adsorption of the collector on the mineral surface.
Due to the large variation of the content of each component of the water glass, the inhibition effect varies with the pH value of the pulp. The conditions at the time of use should be strictly controlled. Because it is easily affected by carbon dioxide in the air, silicic acid is precipitated and the inhibitory effect is affected, so it cannot be placed in the air for too long when used. In order to improve the selectivity of water glass inhibition, it is often used in combination with metal salts such as FeSO4 and sodium carbonate, or by using pulp to heat. Water glass is usually formulated into a 5-10% solution. The amount varies depending on the purpose of use: when used as an inhibitor, the amount is 0.2-2 kg/ton; when used as a slime dispersant, the amount is about 1 kg/ton.
Starch is a high molecular polymer composed of glucose units, and the molecular formula can be simplified to 62%-82% of starch in (C 6 H 10 O 5 ) rice. Starch molecules have two different structures: one is a linear chain starch; the other is a branched gum starch. The latter accounts for about 75% of the starch granules, and the former accounts for about 25%. Chain starch is soluble in water, and gelatin starch is insoluble in water but can swell in water.
Do flotation of quartz with a cationic collector, starch suppressed hematite; copper Mo concentrate was separated, starch molybdenite suppressed, it can be used as a selective flocculant fine hematite.
Dextrin , when the starch is heated to 200 ° C, it will decompose into smaller molecules, which is dextrin. It is a gelatinous substance, soluble in water, primarily as quartz, talc, sericite, etc. inhibitors.
A derivative of cellulose , which is generally insoluble in water, can be converted into a water-soluble derivative such as hydroxyethyl cellulose or carboxymethyl cellulose after chemical treatment.
Hydroxyethyl cellulose (cellulose No. 3 C5H5O2(OH)2.CH2OCH2OH). When flotation of quartz with a cationic collector, it can be used as a selective flocculant for hematite and as a selective inhibitor of calcium and magnesium alkaline gangue. There are two kinds of hydroxyethyl cellulose in industrial products, one is sodium hydroxide solution, insoluble in water, and the other is water-soluble.
Carboxymethylcellulose (No. 1 Cellulose CMC (C 6 H 7 O 2 OH 2 OCH 2 COOH) n) is a water-soluble cellulose wide application. Carboxymethyl cellulose treated with reed as raw material, used for flotation of nickel sulfide ore, as a calcium and magnesium mineral inhibitor. Made from raw materials made from straw, it can inhibit magnetite, hematite, calcite , and silicate minerals such as quartz and smectite activated by CA 2+ and Fe 3+ .
Tannins (plant tannins) are commonly used to inhibit minerals containing calcium and magnesium, such as calcite, dolomite, etc., which are colloidal and soluble in water.
Sodium humate (ammonium) is a rear brown coal treated with sodium hydroxide to give the sodium humate solution. In the reverse flotation of iron ore containing limonite, hematite or iron carbonate, quartz is floated with a reagent such as lime, sodium hydroxide and crude sulfate soap. At this time, ammonium humate (nano) is used to suppress iron. mineral.
The main use of lignin is to inhibit silicate minerals and rare earth minerals. Lignosulfonates can be used as inhibitors of iron minerals. When flotation of potassium salt , it can act as a de-claying agent to remove insoluble slime.
2 ) Activator
The role of the activator is to create a film on the surface of the mineral that acts with the collector, enhances hydrophobicity, and improves floatability. Commonly used activators are: sulfuric acid, hydrochloric acid, copper sulfate, sodium sulfide, and the like.
Copper sulphate ( CuSO4 ) is an activator of sphalerite and can also activate minerals such as pyrite and pyrrhotite. The activation of sphalerite by copper sulfate is due to the ion exchange adsorption of Cu2+ in copper sulfate and Zn2+ in sphalerite, which produces copper sulfide and produces an active surface which can interact with xanthate. The situation is that Cu2+ can precipitate or complex the CN-, SO2-plasma in the slurry, promote the dissolution of the original inhibitory film on the mineral surface, and then form an activated film on the mineral surface. Therefore, copper sulfate can activate minerals suppressed by cyanide or the like. Because copper sulfate is easily hydrolyzed, in order to ensure sufficient Cu2+ in the slurry, the pH value and mixing time of the slurry should be controlled during use.
Calcium chloride, calcium oxide, and barium chloride can be used as activators for fatty acid collectors.
Flotation activator D2 (2,5-dithiol-1,3,4 thiodiazole) DMTDA , which is an organic activator, looks orange-red to dark-purple. The density was 1.35 g/cm 3 and the pH was >13. It is miscible with water and can be added directly without dilution when used. D2 is used as an activator, and xanthate is used as a collector to float copper oxide ore. It can significantly improve the flotation rate of copper oxide ore, improve product quality and increase metal recovery rate. Activator D2 is used in an amount of 0.5-2.5 kg/t ore, typically 0.5-1.5 kg/t ore.
Polyethylene glycol or ether can be used as an activator of gangue minerals. For example, when it is floated in a polymetallic sulphide ore, it can be added together with a foaming agent to select a large amount of gangue, and then a mixture of copper, lead and zinc. selected.
Industrial oxalic acid is used to activate the inhibited pyrite and pyrite.
Calcium chloride, calcium oxide, and barium chloride can be used as activators for fatty acid collectors.
3 ), medium conditioner
Its role is to adjust the nature of the flotation medium (slurry solution), causing the action of the agent and the mineral phase and the conditions required for the flotation process. The adjustment of the medium adjuster mainly includes: adjusting the pH value of the slurry; adjusting the activity of the agent; eliminating the influence on the harmful ions of the flotation; dispersing and agglomerating the slime (such as flocculation).
Increase alkalinity conventional lime slurry or sodium carbonate, caustic soda or sodium sulfide is sometimes used; increase the acidity of used sulfuric acid slurry, followed by hydrochloric acid, nitric acid, phosphoric acid and the like. The pH of the pulp often directly or indirectly affects the floatability of the mineral. Practice has proved that when the temperature of the pulp and the concentration of various chemicals are certain, the pH value of a certain mineral floating and non-floating is called "critical pH".
Critical pH of sulfide ore in a concentration of 25 mg/l xanthate solution (18 ° C)
Lime ( CaO ) is the most widely used pH adjuster in the selection of non-ferrous metal minerals; it is often used to increase the pH of pulp and inhibit iron sulfide due to its low cost, wide source and strong alkalinity. Object. It can also meet and meet this need based on the different mineral pH requirements of various minerals.
When sorting copper-bearing pyrite, the pH value is required to be as high as 11 or more;
When sphalerite is separated from pyrite, a pH of 9 or more is required;
When using xanthate to collect sulfide ore, the pH should be kept above 7;
When cyanide is used to suppress sulfide ore, the pH should be kept above 7.
Lime is a potent inhibitor of sulfide (pyrite, pyrrhotite, pyrite) during flotation of sulfide ore. In addition, since the Ca2+ ion has an inhibitory effect on the lead ore, generally, the lime is not used to adjust the pH value of the slurry, but is adjusted with sodium carbonate. If lime is required to inhibit the pyrite, it is necessary to control the amount of lime.
In the production practice, the specific choice of which regulator depends on the type of minerals selected.
Sodium carbonate (Na2CO3 ), also known as soda , is also the main pH adjuster for the selection of non-ferrous metal sulfide minerals. Sodium carbonate generally adjusts the pH range of the slurry to about 8-10. The advantage is that it can eliminate the harmful effects of Ca2+, Mg2+, etc. in the slurry, and at the same time reduce the adverse effects of the slime on the flotation. However, since sodium carbonate has an activation effect on pyrite, lime should be selected as a pH adjuster when flotation of minerals containing pyrite.
In addition, sodium hydroxide (NaOH), caustic soda, ammonium hydroxide, etc. are also strong alkaline pH adjusters; because of the relatively high price, the use is not as extensive as lime and sodium carbonate.
Sulfuric acid is commonly used to adjust the acidity of the slurry, followed by hydrochloric acid, nitric acid, phosphoric acid, and the like.
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