Northwest Molybdenum Ore is a medium-sized multi-metal gold reserves containing molybdenum deposit. The ore is mainly oxidized ore, the molybdenum oxide mineral is mainly molybdenum-calcium ore, and the small amount is molybdenum, and the ore oxidation rate is as high as 68.5%. Molybdenum sulfide is molybdenite. Gold is mainly distributed in quartz vein ore, and the inlaid features are mainly fine-grained gold.
The ore composition is relatively simple, the valuable elements are mainly molybdenum, and the other non-molybdenum sulfide ore content is low. The molybdenum mineral inlay has a coarser particle size, the monomer dissociation is easy, and the selectivity is relatively good. The content of impurities and minerals in the ore that affect gold leaching is low. Molybdenum is mainly used for the production of molybdenum and molybdenum iron smelting chemical products, and such processes in which the gold can not be recovered, and when gold is not sold molybdenum concentrate pricing [1], so this type must ensure molybdenum ore sorting Under the premise of the index, solve the problem of comprehensive recovery of gold in molybdenum ore to make better use of mineral resources.
First, the nature of the ore
The main mineral composition and content of ore: molybdenum ore 0.32%, molybdenum 0.13% / molybdenum ore 0.32%, scheelite 0.17%, pyrite 0.24%, hematite 3.90%, quartz 57.5%, feldspar 19.6% Calcite is 1.8%. Multiple analysis results of ore: Mo0.52%, WO0.08%, Cu0.01%, S 0.42%, TFe 2.12%, SiO 2 71.5%, A1 2 O 3 8.22%, CaO1.86%, MgO0.55% , As0.012%, C is fixed at 0.03%.
The results of molybdenum phase analysis in ore: 31.50% molybdenum in molybdenum sulfide, 23.24% molybdenum in molybdenum, and 45.26% in molybdenum ore.
Molybdenum ore is mainly symbiotic with quartz, the rest accounts for 1.82% in pyrite and 0.55% in hematite. Molybdenum oxide minerals are mainly distributed in gangue fissures, which are light yellow or khaki aggregates. Most of them retain the shape of molybdenite crystals, which are weathered and easy to mud. The molybdenum mineral is unevenly embedded in the thickness and is mainly composed of fine particles. Gold is mainly composed of microscopic gold and sub-microscopic gold. It is mainly composed of fissure gold and gold-coated in quartz veins. It is rare to have a symbiotic relationship with iron minerals.
Second, the beneficiation test
The process used in the test: raw ore crushing, a rod grinding, molybdenum sulfide flotation, molybdenum oxide flotation, a sulfide ore concentrate, inhibition of molybdenite, one cyanide leaching, an activated carbon suction.
Ore crushing and selective grinding test: The main purpose of the flotation test is to recover molybdenum minerals. Because the molybdenum oxide in the ore is weathered and easy to be muddy, selective molybdenum must be used to avoid molybdenum oxide minerals as much as possible. Grinding and mud loss. After the sample was pulverized to -2 mm by a conventional crushing device, a selective grinding comparison test of the ball mill and the rod mill was performed. The particle size of the product was measured by sieve analysis with a 0.074 mm sieve, and the dissociation degree of the mineral monomer was examined by a microscope. -10 μm particle size was subjected to hydraulic sedimentation analysis to detect the amount of secondary slime produced by crushing and grinding.
Sulfide ore molybdenum gold mixing and floatation process test: In the molybdenum gold mixed floatation test, it is necessary to ensure the concentrate grade of molybdenum sulfide, so that the quality of molybdenum concentrate can be sold as standard [2] , and at the same time, molybdenum and associated materials should be improved as much as possible. The recovery rate of gold. To this end, a collector Comparative Experiment sulfide ore, coal oil as the main collector, secondary butyl xanthate, tetrabutylammonium aerofloat polar collector molybdenite flotation experiments performed [3].
Molybdenum oxide flotation test: Flotation test determines sodium carbonate as pH adjuster; modified water broken glass is mineral sludge dispersant and gangue inhibitor, and hydrocarbyl phosphonate ammonium RJT is used as collector for flotation test [4 ] .
Molybdenum sulfide detoxification inhibits molybdenite test: Molybdenum ore has very good natural floatability, especially after the collector of the mineral surface absorbs the floatability, and the cyanide leaching completely floats on the surface of the slurry. Therefore, it is impossible to directly cyanide leaching gold from the molybdenum sulfide gold mixed concentrate, and it is necessary to remove the drug and suppress the molybdenite to carry out cyanidation leaching. Cyanide leaching - activated carbon adsorption: cyanidation leaching - experimental study on adsorption conditions of activated carbon, by optimizing the test conditions, gold is better recovered.
Third, the results and discussion
(1) crushing and grinding
Molybdenum oxide ore is soil-like and shell-like, with soft texture and easy muddy. It was found that the crushing machine was coarsely crushed by the impact crusher and the fine crushing of the roller crusher was better for the crystal protection [4] . The sample was crushed to -2 mm and subjected to a grinding fineness test. The grinding fineness is too coarse, and the dissociation of useful minerals is insufficient, resulting in low molybdenum oxide selection index and excessive impurity content in the concentrate, which is unfavorable for further chemical treatment of the molybdenum oxide concentrate. Microscopically, the results show that when the grinding fineness reaches -0.074mm, which accounts for 65%, 95% of the molybdenum minerals have reached the monomer dissociation. In the test, it was found that the rod mill was selected for fine grinding. The amount of primary sludge of -10μm in the grinding product was significantly lower than that of the ball milled product. The mineral processing technical index was obviously better than that of the ball mill. Compared with ball milling, the grade of molybdenum oxide in concentrate is increased by 3.5% and the recovery rate of molybdenum is increased by 5%. Under the same fineness, the selection index of molybdenite and gold is not much different.
(2) Sulfide ore flotation
Kerosene and 2# oil were used as flotation reagents for molybdenite, and the dosages were 180 g/t and 90 g/t, respectively. Because the main sulfide ore in the ore is molybdenite and other non-molybdenum sulfide ore is low in content, it can assist the use of other polar collectors to enhance the collection of associated gold in molybdenite and ore. A comparative test of polar collectors was carried out using one rough selection, three sweeps, and six selected processes. The test results are shown in Table 1.
It can be seen from the comparison test of the polar collector that the recovery rate of molybdenum is lower and the recovery rate of gold is the lowest without the addition of the polar collector. In order to increase the recovery rate of gold, an auxiliary polar collector must be used. Among the polar collectors, the effect of butyl xanthate is poor, and the effect of butylammonium black drug and Y89 is equivalent. Considering the selection of butylammonium black drug as a polar collector, the dosage is 15g/t.
(III) Oxidation ore flotation test
Sodium carbonate is used as the pH adjuster, the dosage is 1500g/t; the modified water glass is the inhibitor of gangue mineral, the dosage is 800g/t; POT is the collector, the dosage is 350g/t. The oxidized ore flotation test was carried out by using a rough selection process, three sweeps, three selections, and one fine sweeping process. The test results are shown in Table 2.
The crude concentrate obtained by oxidation ore floatation has a low grade of molybdenum, which does not meet the minimum quality requirements for the sale grade of molybdenum concentrate and must be chemically treated. Now, an acid extraction method is used for extracting, extracting, and extracting an ammonia precipitation or adding a base to roast water to immerse an ion exchange-acid precipitation process. The obtained molybdenum oxide coarse concentrate can be processed by the above two methods to obtain a molybdenum chemical product having a grade of more than 52%.
(4) Desulfurization of molybdenum sulfide concentrate to inhibit molybdenite test
Molybdenum ore has natural floatability, molybdenum concentrate cannot be directly cyanide leaching, and it is necessary to remove the drug and inhibit the leaching process of molybdenite to proceed smoothly. The molybdenum concentrate can be satisfactorily leached after calcination at 550 °C for 3 h. However, the molybdenum roasting equipment is more complicated, and the quality requirements of the roasting products are also strict. Therefore, the roasting and leaching processes are not generally used. Recover gold. The experimental study found that the use of sodium sulfide, oxidant and other agents on the removal of molybdenite is poor, and the effect of activated carbon is better. Granular activated carbon is used as a desorbent and gold adsorbent. The results of drug-free test showed that after molybdenum ore flotation, the conventional dextrin, calcium lignosulfonate, carboxymethyl cellulose and other agents had a poor inhibitory effect, and under the condition of large dosage, it could not be Molybdenum ore is completely inhibited, and some molybdenum sulfide is suspended in the slurry, and the gold leaching rate is low. The modified starch PPG as a molybdenite inhibitor has the characteristics of small dosage and good inhibition effect. The molybdenum ore can be completely inhibited at a dosage of 1200 g/t.
(5) Cyanide leaching test of molybdenum sulfide concentrate
The molybdenum ore dressing enrichment is relatively high, the gold grade in the molybdenum concentrate is higher, and the gold recovery rate is lower. After the molybdenum sulfide concentrate was detoxified and the molybdenum ore was inhibited, the leaching conditions were tested. The test used NaOH to adjust the pH value to >12, the sodium cyanide dosage to 2.8 kg/t, the leaching time to 36 h, and the liquid-solid ratio to 3:1. The test results are shown in Table 3.
After the cyanide leaching of molybdenum concentrate, the gold leaching rate was 93.2%, the activated carbon adsorption rate was 97.6%, the gold leaching adsorption rate was 91.0%, and the total metallurgical recovery was 57.81%.
Fourth, the conclusion
(1) The molybdenum in the natural world is mainly molybdenite, mainly for the easy selection of sulfide ore. The molybdenum in the test sample is dominated by oxidized ore, and molybdenum is the main element of ore recovery. The gold grade associated with the ore is low, mainly microscopic gold and submicroscopic gold. The flotation method is used to enrich gold in the molybdenum sulfide concentrate. The molybdenite enrichment ratio is large, and the gold grade in the molybdenum concentrate is higher, but the recovery rate of gold is lower.
(2) During ore crushing and grinding, the molybdenum oxide ore should avoid excessive pulverization, otherwise the recovery rate of molybdenum oxide will be greatly reduced. The recovery of molybdenum oxide ore is mainly based on flotation, and the flotation agent used must have good selectivity. After the chemical treatment of the molybdenum oxide coarse concentrate, qualified molybdenum chemical products can be obtained.
(3) The molybdenum sulfide concentrate has good natural floatability and cannot be directly cyanated and leached with gold. It must be removed and the cyanide leaching process of molybdenum ore can be smoothly carried out. Activated carbon has the dual function of drug removal and adsorption. After pretreatment of molybdenum concentrate, a good technical index of gold cyanide is obtained.
[references]
[1] Lin Chunyuan. Molybdenum ore beneficiation and deep processing [M]. Beijing: Metallurgical Industry Press, l996.
[2] Ren Juishi. Handbook of Development and Utilization of Industrial Mineral Resources [M]. Wuhan: Wuhan University of Technology Press. 1993.
[3] Wang Dianzuo. Principle and application of flotation agent [M]. Beijing: Metallurgical Industry Press, 1982: 222.
[4] Liu Xuesheng, et al. Experimental study on flotation of molybdenum oxide minerals [J]. Nonferrous Metallurgy and Metallurgy, 2004 (6): 12-14.
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