In the flotation, the inhibitory mechanism of the inhibitor is mainly:
1. Form a hydrophilic film on the surface of the ore particles to achieve the purpose of inhibition.
Inhibition of one of sphalerite is cyanide CN- sphalerite hydrophilic surface film of zinc cyanide.
ZnS]ZnS+2CN-=ZnS]Zn(CN)2+S2-
Inhibition of quartz pyrite, in addition to inhibition of Ca2 + from external energy, mainly pyrite surface OH- effect Fe2 +, and open into insoluble hydrophilic ferrous hydroxide (Fe (OH) 2) and hydrogen Iron oxide [Fe(OH)3] film inhibits pyrite. When the pyrite is acted as a xanthate, a hydrophobic film of iron xanthate is formed on the surface of the pyrite, and OH- can replace the xanthogen ion to form a ferrous hydroxide film on the surface thereof. The response is as follows:
FeS2]Fe(ROCSS)2+2OH-= FeS2]Fe(OH)2+2 ROCSS-
The inhibitory effect of zinc sulphate on sphalerite is also that zinc sulphate reacts with OH- in the alkaline pulp to form zinc hydroxide, which is a hydrophilic colloid, which is also adsorbed by the surface of the granule to cover a part of the collector . In addition, Zn(OH)2 will form a more hydrophilic HZnO22- under the condition of higher pH, which can enhance the inhibition of sphalerite.
Inhibition of the weight of lead chromate other ore is converted to weakly alkaline pulp as chromate, SO42- and then exchanged on the oxidized surface of galena, hydrophilic form insoluble chromium The lead acid film is suppressed. The reaction formula is:
Cr2O72-+2OH-=2CrO42-+H2O
PbS]PbSO4+CrO42-=PbS]PbCrO4↓+SO42-
As the inhibitor of non-sulfurized ore, water glass is inhibited by the hydration of HSiO3- and silicic acid colloidal particles directly adsorbed on the surface of the ore particles, making the surface of the ore particles hydrophilic, due to HSiO3- and H2SO3 and silicic acid. The surface of the salt is adsorbed, so the water glass has a strong inhibitory effect on these minerals.
Many organic colloids, such as water gel, starch, etc., are dispersed in water into a number of molecules of hydrophilic colloidal particles, which can be adsorbed on the surface of minerals such as mica and graphite to be inhibited.
The inhibitor can also form an ion-adsorbing film on the surface of the mineral to inhibit the mineral. When the adsorption potential of the mineral surface to the highly hydrating ions is higher than that of the collector ions, the mineral is inhibited by the surface hydrophilic ions. The HS- and S2- formed by dissociation of sodium sulfide in the slurry can adsorb on the surface of the sulfide ore and prevent the sulfide ore from interacting with the collector.
Carboxymethylcellulose is widely used to inhibit calcium silicate minerals and carbonaceous gangues and argillaceous gangues. The inhibition of cellulose is because after it interacts with the ore particles, it can be combined with water by polar groups such as -O-, -OH, -COOH, and becomes hydrophilic by the ore particles acting on it.
2. Dissolve the hydrophobic mineral surface film in multi-metal mixed sulfide ore flotation concentrate isolated, to be separated due to the mineral surface hydrophobic film has been generated one xanthate. When cyanide is used as an inhibitor, it can interact with the polymetallic xanthate to replace the xanthate anion, such as with ethyl xanthogen:
Zn(C2H5OCSS)2+4CN-=Zn(CN)42-+2C2H5OCSS-
3. Dissolution of the activated film The surface of the sphalerite is activated by Cu2+ to form a copper sulfide film, and the floatability is improved. After cyanide, the copper-cyanide complex is formed by CN- and CU2+, and the activated film of copper sulfide is dissolved. The reaction formula is as follows:
ZnS]CuS+4CN-=ZnS]+S2-+Cu(CN)42-
4. Elimination of activated ions The inhibition of sulfite and thiosulfate is because they are strong reducing agents, which can reduce high-valent metal cations (such as Cu2+) or form complex ions in the slurry, thereby eliminating metals. Activation of ions. Sulfuric acid and its salts, sodium thiosulfate, react in the slurry as follows:
SO2+H2O=H2SO3
H2SO3=2H++SO32-
Na2SO3=2Na++SO32-
Na2S2O3=2Na++S2O32-
SO32-+2Cu2++H2O=2Cu++SO42-+2H+
2S2O32-+2Cu2+=2Cu++S4O62-
The cuprous compound is very unstable and it quickly reacts with the sulfate ion to form thiosulfate sulfate:
2Cu++ 2S2O32-= Cu2(S2O3)22-
One of the inhibitory effects of cyanide is also the ability to remove activated ions. When Cu2+ encounters CN-, a precipitate or complex is formed and removed.
Cu2++2CN-=Cu(CN)2
2Cu(CN)2= Cu2(CN)2↓+2CN-
If there is excess CN-, the precipitated Cu2(CN)2 will be redissolved to form a stable complex ion [Cu(CN)3]2-:
Cu2(CN)2+4CN-=2[Cu(CN)3]2-
This prevents the activity of Cu2+. Commonly used inhibitors are shown in Table 6-6.
Table 6-6, commonly used inhibitors
Serial number | Pharmacy name | Molecular formula | use |
1 | Potassium cyanide | KCN | In the case of separation of non-ferrous metal sulfide ore, inhibition of sphalerite, pyrite, chalcopyrite |
2 | lime | CaO | Inhibition of pyrite |
3 | Potassium dichromate (sodium) Potassium chromate (sodium) | KCr2O7 | Inhibition of galena |
4 | Sodium sulfide | NaS | Used in combination with other chemicals to inhibit zinc, iron sulfide, galena, etc. |
5 | Zinc sulfate | ZnSO4 | Inhibition of sphalerite |
6 | Sulfurous acid or sulfur dioxide | SO2 | Inhibition of sphalerite and iron sulfide ore |
7 | starch | (C6H10O5)n | Inhibition of red iron ore |
8 | Carboxymethyl cellulose | The molecular formula of cellulose is (C6H10O5)n, and the carboxymethyl cellulose is -CH2COOH is substituted for H in the methanol base of cellulose. | Inhibition of calcium magnesium silicate minerals and carbonaceous gangue, argillaceous gangue; such as pyroxene, hornblende, kaolin, serpentine, chlorite, quartz, etc. |
9 | Water glass | Na2SiO3 | Inhibition quartz, silicates and aluminum silicate gangue minerals |
10 | Partial sodium phosphate | (NaPO3)n | Inhibition of apatite, calcite , barite , phosphorous shale , mudstone, etc. |
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