In recent years, the international market of molybdenum metal prices have been steadily rising. However, China's molybdenum mine ore, which is a major exporter of molybdenum metal, is becoming more and more depleted. The grade and recovery rate of the molybdenum concentrate of the beneficiation is affected. Therefore, the rational development and utilization of molybdenum-rich ore has become an important research topic in the field of mineral processing.
Jilin Daheishan Molybdenum Mine is the second largest reserves of molybdenum deposits in Asia. Most of its ore is molybdenum-rich ore, and its molybdenum content is generally about 0.1%. At present, Jilin Nickel Industry Group Co., Ltd. is preparing to build a 3000t/d molybdenum flotation plant to treat the ore. The ore dressing test of the ore is extremely important for the development of this large deposit and the rational use of molybdenum resources. It also seeks a feasible way for the gradual depletion of molybdenum ore in China.
Experimental study by the nature of the ore on the basis of, for ore and partially oxidized low grade molybdenum, molybdenite disseminated mainly of fine particles in the gangue, the ore containing pyrite, yellow copper ore is relatively high, and It contains many features such as easy muddy gangue minerals. After a coarse grinding ore and coarse concentrate are selected, the concentrate is re-grinded and re-selected, and the fine tailings are re-sweeped and discarded as the second tailings process. The lime is used to inhibit pyrite and water glass dispersion to inhibit slime. gangue sulfide inhibition chalcopyrite, kerosene as collector, pine oil as a pharmaceutical conditions foaming agent, the ore is obtained 0.1063% molybdenum (Mo oxidation rate of 12.26%), 0.078% copper, molybdenum concentrate containing An ideal indicator of 47.05% molybdenum, 0.16% copper, and 88.14% molybdenum recovery.
First, the nature of the ore
(1) Composition of ore material
The Daheishan molybdenum ore contains more minerals and less metal minerals, which is 3.79% in total, of which pyrite accounts for up to 2.51% (66.23% of metal minerals). Non-metallic minerals are mainly composed of quartz and feldspar , and contain many easily muddy minerals. The statistical results of the mineral content in the ore are shown in Table 1.
Table 1 Statistics on ore mineral content /%
Metal mineral | Non-metallic mineral | ||
name | content | name | content |
Pyrite | 2.51 | quartz | 52.93 |
Chalcopyrite | 0.33 | Feldspar | 22.44 |
Sphalerite | 0.03 | Black mica | 2.57 |
Galena | 0.05 | muscovite | 3.21 |
Molybdenite | 0.26 | Calcite | 3.84 |
Titanium ore | 0.30 | Swine | 0.32 |
Limonite | micro- | Kaolin | 3.20 |
Copper ore | micro- | Apatite | micro- |
Copper blue | micro- | Zircon | micro- |
Copper ore | micro- | Meteorite | micro- |
Hematite | 0.31 | Sericite | 7.70 |
The results of multi-element analysis of raw ore are shown in Table 2.
Table 2 Multi-element analysis results of raw ore /%
element | Cu | Mo | Pb | Zn | Fe | Mn | As | S |
content | 0.078 | 0.106 | mark | 0.014 | 2.11 | 0.036 | 0.021 | 1.68 |
element | Re | CaO | TiO 2 | Na 2 O | Al 2 O 3 | MgO | SiO 2 | |
content | mark | 0.018 | 0.50 | 0.073 | 12.39 | 0.378 | 68.48 |
The results of analysis of the ore molybdenum phase show that molybdenum accounts for 0.093% of molybdenum sulfide, molybdenum oxide accounts for 0.013%, and molybdenum oxidation rate is 12.26%.
(2) Grain size and output characteristics of molybdenite
The molybdenum ore in the ore is mainly fine particles, of which +0.1mm only accounts for 11.99%, and /37μm accounts for 34.56%, as shown in Table 3.
Table 3 Statistical results of molybdenite dip dyeing/%
Size/μm | +150 | -150+100 | -100+75 | -75+56 | -56+37 | -37 | total | |
Ore type | Test lean ore | 4.53 | 7.46 | 9.48 | 18.38 | 25.79 | 34.36 | 100.1 |
Since the molybdenum oxidation rate of the ore is 12.26%, there is no effective beneficiation method for molybdenum oxide minerals at home and abroad, and because of the fine grain size of molybdenum ore, the ore contains more clay minerals such as kaolin and sericite. In the grinding, a large amount of slime is inevitably produced, and the content of pyrite and chalcopyrite is relatively high, which will adversely affect the quality and recovery rate of molybdenum concentrate and increase the difficulty of the sorting process.
Second, flotation test research
(1) Exploration of process pre-selection test
Considering the characteristics of ore and economic factors, a comparative test was carried out on a section of grinding, multiple selections, a section of coarse grinding, and a refinery refining process. A grinding fineness of -75μm accounted for 65%, and the coarse concentrate was re-examined. The grinding degree is -75μm, accounting for 90%, the coarse sweeping agent is lime, water glass, the collector is kerosene, and the foaming agent is pine oil, which is selected five times. The selected agents are water glass and sodium cyanide. The test results are shown in Table 4.
Table 4 Comparison results of different processes in pre-selection test /%
Process plan | product name | Yield | grade | Recovery rate | ||
molybdenum | copper | molybdenum | copper | |||
Grinding | Molybdenum concentrate | 0.17 | 26.470 | 7.13 | 42.25 | 15.32 |
Molybdenum tailings | 7.20 | 0.638 | 43.10 | |||
Molybdenum sweep concentrate | 2.60 | 0.117 | 2.82 | |||
Tailings | 90.03 | 0.014 | 11.83 | |||
Raw ore | 100.0 | 0.1065 | 100.0 | |||
Rough grinding | Molybdenum concentrate | 0.14 | 35.50 | 9.22 | 45.40 | 16.33 |
Molybdenum tailings | 6.90 | 0.602 | 39.00 | |||
Molybdenum sweep concentrate | 1.76 | 0.114 | 1.88 | |||
Tailings | 91.20 | 0.016 | 13.72 | |||
Raw ore | 100.0 | 0.106 | 100.0 | |||
It can be seen from Table 4 that the refined concentrate grade and recovery rate after regrind of the coarse concentrate are better than those of a section of grinding. For large-scale concentrating plants, the ore has a low grade of molybdenum, and the molybdenum mineral has a fine grain size. It uses a coarse grinding and coarse concentrate re-grinding process to reduce the grinding cost and improve the concentrate index. Technically and economically. It should be the best choice.
(II) Impact of rough selection conditions on indicators
Grinding fineness test, process flow and conditions are shown in Figure 1. The relationship between different grinding fineness and flotation index is shown in Figure 2.
Figure 1 Rough grinding grinding fineness test process and conditions
Figure 2 Relationship between grinding fineness and flotation index
1-molybdenum recovery; 2-molybdenum concentrate grade
It can be seen from Fig. 2 that when the grinding fineness reaches -75μm and accounts for more than 55%, the recovery curve fluctuates above 90%, but the amplitude is not large. This is mainly because the original ore molybdenum has 12.26% of the oxidized ore with the foam mechanical inclusion or even Survival is caused by fluctuations. From the economic point of view, the fineness of the rough-grinding grinding in the -75μm accounted for 55% of the maximum recovery rate of the molybdenite. At this time, the molybdenum ore monomer dissociation degree was 58.83%.
The influence of lime and water glass on the selection index of the coarse selection adjuster is shown in Figure 3.
Figure 3 Relationship between rough selection modifier and flotation index
1- Molybdenum recovery rate with water glass; 2 - Molybdenum grade with water glass;
3-Molybdenum recovery rate with lime; 4-Molybdenum grade with lime
It can be seen from Fig. 3 that when the amount of lime is between 1000 and 1500 g/t, the recovery curve of molybdenum reaches a higher value. At this time, the pH value of the slurry is 7.5 to 8.0, and the recovery curve of molybdenum greater than or less than this amount is significantly decreased. From the point of view of the amount of water glass, the inhibitory effect of dispersing slime and gangue is obvious with the increase of dosage. The molybdenum grade and recovery curve of coarse concentrate have different degrees, but when the dosage reaches 500g/t or more At the time, the recovery rate has decreased.
Due to the low molybdenum grade of the ore and the fine grain size of the molybdenum ore, the coarse selection mainly focuses on increasing the recovery rate of molybdenum. The comparison of the kerosene is better, and the dosage is less, 40g/t. The pine oil in the foaming agent is better than other foaming agents in an amount of 25 g/t.
(3) The impact of the selection process and conditions on the selection indicators
1. The necessity of selecting before re-grinding
Because the coarse concentrate still contains a certain amount of slime, some of the floatable pyrite and the gangue minerals such as kaolin and mica are contained in each other. After regrind, the slime will be further increased. Seriously affect the next step to improve the grade and recovery rate of molybdenum concentrate, and deteriorate the separation process of molybdenum and copper. It must be removed before grinding. The ideal effect is achieved by adding lime and water glass before the re-grinding. The two selections can reduce the yield before regrind from 5.5% to 6.0% of the coarse concentrate to less than 0.5%. Grade molybdenum is increased from 2% to 3% to more than 20%. The recovery rate of molybdenum is over 83.0% (the recovery rate of work is over 90%). It can be seen that the effect of re-grinding before re-grinding is obvious, which not only reduces the re-grinding load, but also improves the molybdenum grade. It also creates favorable conditions for the subsequent re-grinding and copper suppression, and is a necessary step in the process of processing such ore.
2. Influence of fine grinding refinement on selected indicators
The process flow is shown in Figure 4. The relationship between regrind and selected indicators is shown in Figure 5. (Because the two concentrates are too small before regrind, the test and subsequent copper inhibitor tests are taken before re-grinding) .
Figure 4 Concentrate regrind test and conditions
Figure 5 Relationship between regrind and flotation index
1-molybdenum recovery; 2-molybdenum concentrate grade
It can be seen from Fig. 5 that after re-grinding, the molybdenum concentrate grade is obviously improved when the molybdenum recovery rate is not changed, and the refining is 6 min (-75 μm, 92%), which is improved by 17.14% which is no longer grinded. To 25.06%, the molybdenite monomer dissociation degree was 88.31%. If the grinding time is increased, the mineral mud will be seriously affected, which will affect the selection effect.
3. Selection of copper inhibitors and copper suppression effect of sodium sulfide dosage
Because the ore contains relatively high copper, it is 0.078%, and due to the action of copper ions generated in the grinding, the difference in floatability between the minerals is reduced. The effect of using sodium cyanide to suppress copper in the pre-grinding test conditions is not satisfactory. After re-grinding, the selected concentrate contains 25.06% of molybdenum containing 7.15% of copper. If a large amount of sodium cyanide is added, it will increase the environmental cost of treating tail water discharge, thereby increasing costs. In order to seek a cheaper and more environmentally friendly copper inhibitor, the copper inhibitor effect of the four inhibitors was investigated. The effect of sodium sulfide on copper inhibition is shown in Fig. 6.
Figure 6 Relationship between sodium sulfide dosage and mineral processing index
1-molybdenum recovery; 2-molybdenum grade; 3-copper recovery; 4-copper grade
From the relationship between the amount of sodium sulfide and the effect of copper inhibition, it can be seen that when the amount of sodium sulfide (re-grinding) is 1200 g/t, the grade of molybdenum concentrate is 45.17% and the content of copper is 0.211% after two selections. When the amount of sodium sulfide is increased to 1500 g/t, the copper content of the molybdenum concentrate is no longer lowered. Therefore, sodium sulfide and copper should be added in an amount of 1200 to 1500 g/t.
(4) After re-grinding, select a tailings and re-elect and abandon the second tailings
After re-grinding, it was selected to remove most of the slime and inhibited most of the copper minerals, but 8.37% of the molybdenum entered the selected tailings. However, a large amount of copper minerals, slime and sodium sulphide in the fine tail, such as closed circuit, will have a vicious cycle, and sodium sulfide will have a certain activation effect on pyrite, and the slime will inevitably affect the final molybdenum. Mine quality and recovery rate. The normal returning closed-circuit test of the middle mine proves that the recovery rate of molybdenum is 84.95%. From the distribution of copper metal, the total tailings plus concentrate is 55.64%, that is, 44.46% of the copper does not enter the tailings in the middle ore. . This will also ultimately affect the quality of molybdenum concentrate, which is a problem that must be solved. Therefore, it is necessary to discard the final tailings after re-polishing the selected tailings. The test procedure and conditions are shown in Figure 7, and the test results are shown in Table 5.
Fig.7 Process and conditions for re-sweeping molybdenum after selective grinding of copper
Table 5 Re-grinding tailings re-sweep test results /%
product name | Yield | grade | Recovery rate | ||
molybdenum | copper | molybdenum | copper | ||
Molybdenum concentrate | 0.16 | 47.813 | 1.563 | 71.89 | 3.28 |
Fine sweep concentrate | 0.05 | 13.400 | 3.970 | 6.30 | 2.63 |
Fine tailings 2 | 0.65 | 1.092 | 0.420 | 6.67 | 3.55 |
Fine tailings 1 | 5.00 | 0.093 | 0.297 | 4.42 | 19.61 |
Fine sweeping tailings | 0.21 | 1.063 | 8.670 | 2.07 | 23.95 |
Coarse tailings | 93.93 | 0.0098 | 0.038 | 8.65 | 46.98 |
Tailings | 100.0 | 0.1064 | 0.076 | 100.0 | 100.0 |
It can be seen from Table 5 that after re-grinding, a selected tailings can be re-selected to obtain 13.40% molybdenum molybdenum concentrate, and the recovery rate is 6.30%. The fine sweeping tailings contain 1.063% molybdenum and the metal distribution rate is 2.07%. If the sweeping is carried out twice or three times, the second tailings can be abandoned, so that the process is reasonable and perfect.
(5) Comprehensive open circuit test
A comprehensive open circuit test was conducted on the basis of various main processes and conditions. The process flow and pharmaceutical conditions are shown in Figure 8, and the test results are shown in Table 6.
Table 6 Comprehensive open circuit test results /%
product name | Yield | grade | Recovery rate | ||
molybdenum | copper | molybdenum | copper | ||
Molybdenum concentrate | 0.12 | 55.333 | 0.251 | 62.40 | 0.39 |
Fine tailings 5 | 0.02 | 35.500 | 2.000 | 6.67 | 0.52 |
Fine tailings 4 | 0.03 | 10.000 | 6.000 | 2.82 | 2.37 |
Fine sweep concentrate 1 | 0.05 | 13.400 | 3.970 | 6.30 | 2.63 |
Fine sweep concentrate 2 | 0.04 | 3.750 | 5.000 | 1.40 | 2.63 |
Fine tailings 2 | 0.65 | 1.0928 | 0.420 | 6.67 | 3.55 |
Fine tailings 1 | 5.00 | 0.0934 | 0.297 | 4.42 | 19.61 |
Sweeping concentrate 1 | 1.70 | 0.220 | 0.137 | 3.48 | 3.03 |
Sweeping concentrate 2 | 0.90 | 0.077 | 0.153 | 0.66 | 1.84 |
Tailings 2 | 0.17 | 0.400 | 9.529 | 0.67 | 21.32 |
Tailings 1 | 91.32 | 0.0053 | 0.035 | 4.51 | 42.11 |
Raw ore | 100.0 | 0.1064 | 0.076 | 100.0 | 100.0 |
Figure 8 Integrated open circuit test process and conditions
It can be seen from Table 6 that the process and conditions of the integrated open circuit test have obtained better selection indicators. The refined molybdenum grade has 55.33% copper, 0.251% copper, 0.0053% tailings 1 molybdenum grade, and 2 molybdenum tailings. Grade 0.40%, containing 9.529% copper, molybdenum only loss recovery rate of 0.67% (can be sold as copper concentrate). At the same time, the molybdenum grade and metal distribution of each mine are reasonable.
(6) Closed circuit test verification
The closed circuit test was carried out on the basis of the integrated open circuit process and conditions. The process flow and conditions are shown in Figure 9. The final test results are shown in Table 7.
Figure 9 Closed-circuit test process and conditions
Table 7 Closed circuit test results /%
product name | Yield | grade | Recovery rate | ||
molybdenum | copper | molybdenum | copper | ||
Molybdenum concentrate | 0.199 | 47.035 | 0.160 | 88.14 | 0.38 |
Tailings 2 | 0.622 | 0.434 | 8.087 | 2.54 | 64.24 |
Tailings 1 | 99.179 | 0.010 | 0.028 | 9.32 | 35.38 |
Raw ore | 100.00 | 0.1062 | 0.078 | 100.0 | 100.0 |
According to the closed-circuit test results, for the low-grade fine-grained molybdenum ore containing copper, sulfur and slime in Daheishan, a coarse grinding is used, and the kerosene and pine oil are roughly selected to maximize the recovery of molybdenum. Add lime and water glass to remove pyrite and ore gangue twice, concentrate and re-sintered with sodium sulfide and copper, select fine tailings twice, and molybdenum sweep concentrate to participate in the selection cycle The fine sweeping tailings are discarded for the second tailings. The process and chemical conditions are a good choice for processing the Daheishan ore. The test finally obtained a higher grade and recovery of molybdenum concentrate.
Third, the conclusion
The Daheishan molybdenum deposit is the second largest molybdenum deposit in Asia. Most of its ore is a low-grade molybdenum ore. Due to the finer molybdenum mineral particles and 12.26% oxidation. Most of the metal minerals are pyrite, which contains relatively high copper, and the gangue mineral contains more easily muddy minerals. This inevitably leads to a complicated mineral processing process, and it is difficult to obtain a good selection index, which has long affected the large-scale development and utilization of this large resource. The technical solution to the problem of sorting the ore with large ore-poor deposits has played a certain role in the sustainable development of molybdenum mining in China.
Due to the current domestic and international removal of water and metallurgy, there is no effective method for the selection of molybdenum oxide ore. The experimental study obtained an ideal index of molybdenum concentrate grade 47.035%, copper containing 0.16%, and molybdenum recovery rate of 88.14%. According to estimates by Jilin Nickel Industry Group Co., Ltd., the construction of the 3000t/d concentrator is technically and economically feasible. If the copper recovery is further strengthened, the comprehensive economic benefits of mineral processing should be considerable.
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