Cu
Pyrite (FeS 2), yellow copper ore (FeCuS 2) are widely distributed sulfide minerals, they are mostly accompanied by symbiotic, floating and can be similar, so they flotation separation has always been an important concern of researchers beneficiation Question. At present, the process of realizing the flotation separation of copper and sulfur minerals in industrial production can be roughly divided into five categories according to the types of inhibitors: cyanide process, lime high alkali process, inorganic inhibitor low alkali process, and redox agent as the core. Chemically controlled flotation process and separation process based on organic inhibitors. Wherein cyanide and toxic environmental pollution due to the process have been eliminated; high-alkali process is a lime separation process currently most widely used, the most mature technology sulfide ore; low alkali inorganic inhibitor technology commonly zinc sulfate and the like as sodium phosphate inhibition The electrochemically controlled flotation process uses K 2 CrO 7 , KMnO 4 , Na 2 S, sulfite, etc. as a slurry potential regulator to achieve selective inhibition of sulfide ore. Brod Bent et al used pyrosulfite to inhibit pyrite, and when it was used at 500 g/t, the best flotation selectivity was achieved. Organic compounds such as dextrin, tannin and humic acid have received extensive attention as inhibitors of pyrite. Tan Xin found that under the on-site process conditions, the new organic inhibitor BK-L has a copper recovery rate comparable to that of the lime process, and the copper concentrate grade is increased by 0.73 percentage points.
The author believes that an important reason for the difficulty in separating pyrite and chalcopyrite is due to the accompanying symbiotic pyrite and chalcopyrite in mineralization, oxidation, various alterations and beneficiation processes (such as grinding, adding sulfuric acid). Copper acts as an activator). The phenomenon of copper ions diffusing and migrating to pyrite causes pyrite to be activated by Cu 2+ and is similar to the surface flotation characteristics of chalcopyrite. Thus, Cu 2+ activated flotation separation of pyrite and chalcopyrite are metal sulfide ore mineral mining common technical problems. From this study, pyrite flotation characteristics of activated Cu 2+, cleaning using a complexing agent is a Cu 2+ activated pyrite surface of copper citrate ions, reducing its original floatability; a reducing agent alkylene Sodium hydrogen sulfate reduces the double xanthate produced on the surface of the pyrite to a single yellow drug, making it easier to desorb; using lime to inhibit pyrite in an alkaline medium. I.e., citric acid - sodium bisulfite - lime composition adjusting agent inhibits Cu 2+ activated pyrite, investigated the effect of flotation separation of Cu 2+ activated pyrite, chalcopyrite under the action of the control agent composition .
First, the sample and test method
The test samples were taken from two mines, Tonglu Mountain and Tongshankou of Daye Nonferrous Metals Corporation. After crushing, hand selection, and ball milling, samples of -100+400 mesh size were taken for flotation test. Through chemical analysis and X-ray diffraction detection, the purity of pyrite ore samples is over 98%, and the purity of chalcopyrite ore samples is over 96%.
The experiment investigated the natural floatability of chalcopyrite and pyrite single minerals in the Dinghuang system, lime (adjusted pulp pH), sodium bisulfite, copper ion to chalcopyrite, pyrite single mineral floatability Effect of citric acid on the flotation of pyrite and chalcopyrite single minerals activated by Cu 2+ , citrate-sodium bisulfite-lime combination inhibitor on pyrite and brass activated by Cu 2+ The effect of flotation of mineral single mineral flotation, and the flotation separation effect of pyrite and chalcopyrite artificial mixed ore activated by Cu 2+ under the action of citric acid-sodium bisulfite-lime combination inhibitor.
2 g of the ore sample was taken for each test, and rough selection was performed once in the RK/FGD type trough flotation machine (25 mL flotation cell). Industrial pure No. 2 oil is used as foaming agent and industrial pure Dinghuang medicine as collector . The remaining chemicals such as copper sulfate, citric acid, sodium hydrogen sulfite, lime and sulfuric acid are all analytically pure. After the flotation is completed, the foam product and the product in the tank are dried and weighed to calculate the recovery rate. When the mixed ore sample is flotation, the foam product is copper concentrate, and the product in the tank is sulfur concentrate.
Second, the test results and discussion
(1) Natural floatability of two single minerals in the butyl yellow drug system
Because of its good harvesting capacity, xanthate is the main collector of sulfide ore flotation. As the number of carbon atoms in the molecule increases, the ability to capture xanthate increases, but the selectivity gradually decreases. Therefore, the flotation of polymetallic sulfide ore is often selected from butyl xanthate. Under the conditions of natural pH (about 6.5) and No. 2 oil consumption of 60 mg/L, the flotation recovery of pyrite and chalcopyrite single minerals is shown in Figure 1 with the change of the amount of Ding Huang. It can be seen that the recovery rates of chalcopyrite and pyrite increase with the increase of the dosage of Dinghuang, but the recovery rate of chalcopyrite is always higher than that of pyrite; When ×10 -4 mol/L, the recovery rates of the two single minerals reached the maximum, which were 96.86% and 93.23%, respectively. Therefore, it was confirmed that a subsequent flotation test was carried out at a dose of 3 × 10 -4 mol/L of Ding.
Figure 1 Two single mineral flotation recovery rates with the amount of Ding Huang
â—†-pyrite; â–²-chalcopyrite
(B) the effect of pH on the flotation of two single minerals
In the sulphide ore flotation process, lime is widely used at a low price and good inhibition performance for pyrite. Using sulfuric acid or lime as a pH adjuster, the pH of the single mineral of chalcopyrite and pyrite is investigated under the condition that the dosage of Dinghuang is 3×10 -4 mol/L and the amount of No. 2 oil is 60 mg/L. The effect of flotation is shown in Figure 2. It can be seen that the chalcopyrite has good buoyancy in the range of pH 4~12, and the recovery rate is less affected by the pH of the pulp. However, after the pH is greater than 12, the recovery rate decreases rapidly. When the pH is 13, the recovery rate is as follows. Only 52.60%; pyrite can be floated under acidic conditions. As the pH of the pulp increases to alkaline, the floatability drops sharply. When the pH is 13, the recovery rate is only 8.51%. At pH=12, the recovery rate of chalcopyrite is still high, and the recovery rates of chalcopyrite and pyrite are quite different.
Figure 2 Effect of pH on the floatability of two single minerals
â—†-pyrite; â–²-chalcopyrite
(III) Effect of sodium sulfite on flotation of two single minerals
As a reducing agent, sodium hydrogen sulfite can adjust the redox potential of the slurry, so that the double xanthate adsorbed on the surface of the pyrite can be reduced to a single yellow drug to be more easily desorbed, or the formation of double xanthate on the pyrite surface is prevented, thereby Strengthening the inhibition of lime on pyrite. The pH of the pulp was adjusted to 12 with lime, and the amount of sodium bisulfite was used for chalcopyrite and yellow under the condition that the dosage of Dinghuang was 3×10 -4 mol/L and the amount of No. 2 oil was 60 mg/L. The effect of iron ore single mineral flotation, the results shown in Figure 3. It can be seen that with the increase of the amount of sodium bisulfite, the recovery rate of chalcopyrite has no obvious change, and the recovery rate of pyrite is rapidly decreased. When the amount of sodium hydrogen sulfite is 4×10 -4 mol/L, yellow Iron ore is almost non-floating. Comparing with Figure 3, it is known that sodium bisulfite does enhance the inhibition of pyrite by pyrite, that is, the sodium bisulfite-lime combination has a stronger inhibitory effect on pyrite than a single lime.
Figure 3 Effect of sodium bisulfite on the floatability of two single minerals
â—†-pyrite; â–²-chalcopyrite
(4) Effect of copper ions on flotation of two single minerals
The effect of Cu 2+ on single mineral flotation of chalcopyrite and pyrite was investigated by adding copper sulfate under alkaline conditions of natural pH and pH = 12, respectively. In the test, the amount of Ding Huang was 3×10 -4 mol/L, and the amount of No. 2 oil was 60 mg/L. The test results are shown in Fig. 4 and Fig. 5. It can be seen that under natural pH conditions, with the increase of the amount of copper sulfate, the recovery rate of pyrite is slightly increased, while the recovery rate of chalcopyrite is not changed; when the amount of copper sulfate is more than 0.5×10 -4 mol/L After that, the recovery rates of pyrite and chalcopyrite are very similar, with no significant difference. Under the alkaline condition of pH=12, with the increase of the amount of copper sulfate, the recovery rate of pyrite is greatly increased first, and reaches a maximum value of 74.74% when the amount of copper sulfate is 0.5×10 -4 mol/L. There is a decline, while the recovery rate of chalcopyrite has not changed much. Comparing with Figure 3, the difference in floatability between pyrite and chalcopyrite activated by Cu 2+ becomes smaller.
Figure 4 Effect of copper sulfate on the floatability of two single minerals at natural pH
â—†-pyrite; â–²-chalcopyrite
Figure 5 Effect of copper sulfate on the floatability of two single minerals at alkaline pH
â—†-pyrite; â–²-chalcopyrite
(V) Effect of citric acid on flotation of two single minerals activated by Cu 2+
Citric acid can complex with copper ions to clean the activated copper ions on the surface of pyrite, thereby restoring the natural floatability of pyrite. First add 0.5×10 -4 mol/L copper sulfate and stir for 2 min to activate the single mineral, then add different amounts of citric acid and adjust the pH of the slurry to 12, and the dosage in Dinghuang is 3×10 -4 mol/L, 2 The effect of citric acid on the flotation of pyrite and chalcopyrite single mineral activated by Cu 2+ was investigated under the condition of 60 mg/L. The test results are shown in Fig. 6. It can be seen that with the increase of the amount of citric acid, the recovery rate of chalcopyrite has no significant change, while the recovery rate of pyrite is significantly reduced. When the amount of citric acid is 3×10 -4 mol/L, it decreases to 43.23%. After that, the decline was not large. Comparing with Fig. 2 and Fig. 5, it can be seen that citric acid can eliminate the activation of pyrite by Cu 2+ and restore its original floatability.
Figure 6 Effect of citric acid on the buoyancy of two single minerals activated by Cu 2+
â—†-pyrite; â–²-chalcopyrite
(6) Effect of combined regulators on flotation of two single minerals activated by Cu 2+
The above experimental studies show that lime has a good inhibitory effect on pyrite, sodium bisulfite can strengthen the inhibition of pyrite by lime, and citric acid can eliminate the activation of pyrite by Cu 2+ . Based on the flow and conditions of Figure 7, the effects of citric acid-sodium bisulfite-lime combination inhibitor on the flotation of pyrite and chalcopyrite single minerals activated by Cu 2+ were investigated. The test results are listed in the table. 1. It can be seen that the average recovery of pyrite is only 10.03%, and the average recovery of chalcopyrite is 87.63%, indicating that the citrate-sodium bisulfite-lime combination modifier acts on the yellow iron activated by Cu 2+ . The ore has good selective inhibition.
Figure 7 Two single mineral activation-combination inhibitor inhibition test procedures and conditions
Table 1 Two single mineral activation-combination inhibitor inhibition test results%
(VII) Separation test of artificial mixed ore flotation activated by Cu 2+
The chalcopyrite and pyrite are mixed in a ratio of 1:3 and mixed into artificial mixed ore. According to the flow and conditions of Figure 7, the copper sulfate solution is first activated, and then the citric acid-sodium bisulfite-lime combination is adjusted. The agent was mixed with Dinghuang and No. 2 oil for flotation separation. However, considering the pH of the slurry was 12, the recovery rate of chalcopyrite was slightly reduced, so the pH of the slurry was adjusted to 11.8. The test results are shown in Table 2. It can be seen that under the inhibition of Cu 2+ -activated pyrite by the citric acid-sodium bisulfite-lime combination modifier, the copper grade and copper recovery rate are 24.12% and 88.48% of copper concentrate, and sulfur grades with sulfur grade and sulfur recovery of 49.69% and 72.51%, respectively, indicate that the combination of modifiers can achieve effective separation of pyrite-chalcopyrite activated by Cu 2+ . .
Table 2 Experimental results of artificial mixed mineral flotation separation test %
Third, the conclusion
(1) Sodium bisulfite as a reducing agent can inhibit the formation and existence of double xanthate on the surface of pyrite, and strengthen the inhibitory effect of lime on pyrite, that is, the inhibition effect of sodium bisulfite-lime combination on pyrite Stronger than a single lime.
(2) Copper ions can activate pyrite, and the difference in floatability between pyrite and chalcopyrite activated by Cu 2+ becomes smaller.
(3) Citric acid can eliminate the activation of Cu 2+ on pyrite flotation and restore its original floatability.
(4) The citric acid-sodium bisulfite-lime combination regulator has a good selective inhibition effect on the flotation of pyrite activated by Cu 2+ , and the yellow regulator activated by Cu 2+ can be realized by using the combination regulator Effective separation of iron ore-chalcopyrite.
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