Xinjiang Qilian copper mine after more than four decades of production, copper sulfide mineral resources drying up, but the top of the mine and the surrounding there are a lot of high grade oxide copper resources. In order to recover as copper resources, to extend the life of the mine, were first studied the oxidation of copper sulfide flotation recovery of copper small test, but the weathered mine, iron containing, high mud, low flotation test results, process and The pharmaceutical system is complex and is not suitable for on-site industrial production. To this end, the Qilian Copper Mine conducted a small acid-dipping test on the ore sample to provide a basis for the feasibility study of the wet acid leaching plant.
First, the sample preparation
The ore samples are mainly derived from the two oxidized ore main ore bodies of the Qilian Copper Mine. Ore processing is formulated at 1:1 and sample processing is performed as required for small tests. Its ore processing and sampling procedures are shown in Figure 1.
Figure 1 Ore processing flow and sampling procedure
Second, the nature of the ore
The prepared ore sample is sent to the central laboratory for analysis of the main elements and phases of the ore. The results are shown in Table 1.
Table 1 Analysis of main elements and phases of ore
element | Cu | Fe | CaO | MgO | Total CuO | Free CuO | Combined with CuO |
content% | 2.845 | 21.90 | 1.678 | 3.648 | 2.435 | 1.252 | 1.183 |
According to the data analysis in Table 1, the ore has the following characteristics: the original ore contains 2.845% copper, the oxidation rate is 68.47%, and the bonding rate is 33.26%. The leaching rate is not expected to be high. Conventionally, if non-oxidized copper (31.65% of total copper) is 100% not leached; easily leached free copper oxide (35.09% of total copper) can be leached; leached copper oxide (accounting for total copper 33.26) %) 50% can be leached, then the leaching rate should be around 51%.
The ore contains iron at a high 21.9%, which consumes a portion of the acid. The content of CaO and MgO is not high and will not affect the copper leaching process. The ore sample has a high degree of muddyness, and the proportion of fine-grained grades is large, which has an adverse effect on leaching.
Third, the grinding sample shock leaching test
The purpose of the grinding-like oscillating leaching test is to study the optimum leaching rate of the ore copper in order to compare the effects of other leaching methods. The test results are as follows.
Leaching conditions: leaching in a 1000ml beaker, loading 200g, ore fineness -200 mesh accounting for 95.8%, leaching solution solid ratio 4:1, using industrial sulfuric acid (density 1.83g/ml, purity 95%), starting The acidity was 69.54g/L, oscillated for 2h, and clarified for 16h. The sample was tested and the leaching solution contained 3.85g/L of copper, 6.75g/L of iron, and the acidity was 47.09g/L.
Leaching results: original ore copper grade 2.845%, iron grade 21.9%, of which copper oxide 2.435%, combined with copper oxide 1.183%, leachate containing copper 3.85g / L, steel leaching rate according to liquid 54.13% (copper oxide leaching rate 79.06%) ), tons of mineral consumption of 89.8kg of sulfuric acid (according to the density of 1.83g / ml, the purity of 95% of industrial sulfuric acid calculation, the same below), converted tons of copper consumption of sulfuric acid 5.83t. The leaching rate of iron is 12.33%.
The test results show that the leaching rate of copper in the sample under laboratory conditions has achieved the desired effect. The binding rate of copper oxide in ore is very high, which affects the leaching rate of copper. The clarification time is long, and the leaching of copper and iron is prolonged for a long time, thereby consuming a part of the acid and increasing the acid consumption.
Four, -5mm comprehensive sample stirring leaching test
The purpose of the -5mm comprehensive sample agitation leaching test is to study the optimum leaching rate of copper under the minimum crushing particle size that can be achieved by the ore on-site production conditions. The seed grade leaching field of the seed grade may be stirred or leached or pooled.
Leaching conditions: leaching in a 1000ml beaker, loading 150g, fineness -200 mesh 11.3%, liquid to solid ratio 4:1, using industrial sulfuric acid (density 1.83g / ml, purity 95%), initial acidity 52.16 g/L, mechanically leached for 2h, placed for 2h clarification, sampled and tested, the leaching solution contained 3.379g/L of copper, containing 0.8g/L of iron, and ending acidity of 50.91g/L.
Leaching results: original ore copper grade 2.845%, iron grade 21.9%, of which copper oxide 2.435%, combined with copper oxide 1.183%, leaching solution containing copper 3.379g / L, according to liquid copper leaching rate of 47.51% (copper oxide leaching rate of 69.38% ), the mine consumes 5kg of sulfuric acid, the consumption of sulfuric acid is 0.37dt, and the leaching rate of iron is 1.46%.
The above results indicate that the ore leaching has a great relationship with the particle size. The less than 5 mm ore sample has a low degree of muddyness and is advantageous for leaching; the iron is hardly leached, so the acid consumption is very low.
Five, trough dip test
The purpose of the tank leaching test is to study the optimum leaching rate of copper under the particle size conditions of the ore in the general production conditions of the site. The ore-level ore is leached, and the tank (pool) immersion is suitable at the site.
The test uses a comprehensive sample of less than 20mm, the dry weight of the ore sample is 9.lkg, soaked in a 15L plastic drum, stirred 2 to 3 times a day, soaked for 2d to pour the leaching solution, and then add liquid.
The results of the tank dip test are shown in Figure 2 and Table 2. According to Table 2, the acid consumption of the tank leaching ore is 9.68kg/t ore, and the acid consumption per ton of copper is 0.87t/t copper. The acid consumption is less than that of the column, and the leaching rate is also significantly lower than that of the column.
Figure 2 Cubic copper and iron cumulative leaching diagram
Table 2 Results of small tank dipping test (1)
Dipping days d | Initial acidity | Leaching composition and content | ||||||
H 2 SO 4 g/L | Volume mL | Cug/L | Feg/L | H 2 SO 4 g/L | Cu Content g | Cumulative Cu Content g | Cumulative Fe Content g | |
2 | 60.85 | 5706 | 9.86 | 1.70 | 53.30 | 56.27 | 9.70 | |
4 | 46.36 | 4000 | 5.25 | 2.68 | 45.07 | 21.00 | 77.27 | 20.42 |
6 | 30.91 | 4000 | 2.43 | 1.76 | 33.36 | 9.72 | 86.99 | 27.46 |
8 | 34.77 | 3000 | 2.47 | 1.46 | 35.01 | 7.41 | 94.40 | 31.84 |
10 | 34.77 | 3000 | 1.29 | 1.76 | 33.46 | 3.87 | 98.27 | 37.12 |
12 | 52.16 | 3000 | 0.79 | 1.55 | 49.98 | 2.37 | 100.64 | 41.77 |
14 | 34.77 | 3000 | 0.31 | 1.55 | 37.90 | 0.91 | 101.55 | 46.42 |
Grand total | 101.55 | |||||||
Continued Table 2 Results of small tank dipping test (2)
Dipping days d | Acid consumption | Cu leaching rate% | CuO leaching rate% | Fe cumulative leaching rate% | ||
g | Same day | Grand total | Same day | Grand total | ||
2 | 43.60 | 21.75 | 25.41 | 0.47 | ||
4 | 28.34 | 8.12 | 29.87 | 9.48 | 34.89 | 1.02 |
6 | 5.64 | 3.76 | 33.63 | 4.39 | 39.28 | 1.38 |
8 | 0.00 | 2.86 | 36.49 | 3.35 | 42.63 | 1.60 |
10 | 3.93 | 1.50 | 37.99 | 1.75 | 44.38 | 1.86 |
12 | 6.53 | 0.92 | 38.91 | 1.07 | 45.45 | 2.09 |
14 | 0.00 | 0.35 | 39.26 | 0.41 | 45.86 | 2.33 |
Grand total | 88.04 | |||||
Six, column immersion test
The purpose of the column leaching test is to study the optimum leaching rate of copper in the heap leaching or in situ leaching process under the conditions of two or a section of the general production conditions of the site.
The column immersion test was carried out in a column of Φ 120 × 800 mm.
Leaching conditions: the ore size of the ore is less than 20mm, the ore content is 9.37kg, the loading height is 590mm, the spraying speed is 2~5ml/min, the spraying is 16h, the idle time is 8h, and the spraying intensity is 13L/h.m 2 .
The results of the column immersion test are shown in Figure 3 and Table 3.
Figure 3 Cucumber and iron cumulative leaching diagram
Table 3 Results of column immersion test (1)
Dipping days d | Initial acidity | Leaching composition and content | ||||||
H 2 SO 4 g/L | Volume mL | Cug/L | Feg/L | H 2 SO 4 g/L | Cu Content g | Cumulative Cu Content g | Cumulative Fe Content g | |
1 | 55.97 | 2986 | 13.69 | 1.75 | 30.72 | 40.88 | 5.23 | |
2 | 52.16 | 2590 | 10.62 | 4.42 | 38.57 | 27.51 | 68.39 | 16.68 |
3 | 34.77 | 3000 | 5.35 | 3.88 | 32.52 | 16.05 | 84.44 | 28.32 |
4 | 34.77 | 3000 | 3.85 | 3.88 | 27.13 | 11.55 | 95.99 | 39.96 |
5 | 34.77 | 3000 | 2.45 | 3.88 | 26.46 | 7.35 | 103.34 | 51.60 |
6 | 34.77 | 3000 | 1.93 | 4.08 | 27.16 | 5.79 | 109.13 | 63.84 |
7 | 34.77 | 2980 | 1.01 | 3.76 | 25.61 | 3.01 | 112.14 | 75.04 |
8 | 52.16 | 2960 | 1.04 | 5.00 | 33.56 | 3.09 | 115.23 | 89.84 |
9 | 34.77 | 3060 | 0.79 | 6.06 | 34.08 | 2.43 | 117.66 | 108.38 |
10 | 52.16 | 2970 | 0.69 | 5.28 | 36.76 | 2.05 | 119.71 | 124.06 |
11 | 34.77 | 2970 | 0.69 | 5.28 | 36.76 | 2.05 | 121.76 | 139.74 |
12 | 34.77 | 3480 | 0.52 | 4.88 | 28.92 | 1.82 | 123.58 | 156.72 |
Grand total | 35996 | 3.43 | 4.35 | 31.40 | 123.58 | |||
Continued Table 3 Column Dipping Test Results (2)
Dipping days d | Acid consumption | Cu leaching rate% | CuO leaching rate% | Fe cumulative leaching rate% | ||
g | Same day | Grand total | Same day | Grand total | ||
1 | 116.89 | 15.33 | 22.39 | 0.25 | ||
2 | 56.56 | 10.32 | 25.65 | 15.07 | 37.46 | 0.81 |
3 | 6.75 | 6.02 | 31.67 | 8.79 | 46.25 | 1.38 |
4 | 22.92 | 4.37 | 35.99 | 6.32 | 52.57 | 1.95 |
5 | 24.93 | 2.76 | 38.75 | 4.03 | 56.60 | 2.50 |
6 | 22.83 | 2.17 | 40.92 | 3.17 | 59.77 | 3.10 |
7 | 27.99 | 1.13 | 42.05 | 1.65 | 61.42 | 3.66 |
8 | 57.12 | 1.16 | 43.21 | 1.69 | 63.11 | 4.38 |
9 | 0.03 | 0.91 | 44.12 | 1.33 | 64.44 | 5.28 |
10 | 47.28 | 0.77 | 44.89 | 1.12 | 65.57 | 6.04 |
11 | -4.87 | 0.77 | 45.66 | 1.12 | 66.69 | 6.81 |
12 | 3.67 | 0.68 | 46.34 | 1.00 | 67.69 | 7.64 |
Grand total | 382.10 | 46.34 | 67.69 | 7.64 | ||
It can be seen from Table 3 that: 1 the results of all the leachate mixing tests are Cu3.25g/L, Fe4.48g/L, H 2 SO 4 32.53g/L, and the cumulative weighted average of Table 3 is Cu3.43g/L, Fe4.35g. /L, H 2 SO 4 31.40g / L, basically consistent. 2 According to Table 3, the acid consumption of column leaching ore is 40.767kg/t ore, and the acid consumption per ton of copper is 3.09t/t copper. It shows that the heap leaching consumes less acid and consumes less acid than stirring and leaching.
Conclusions and recommendations
(1) The ore ore is more complex in nature. The content of CaO and MBO is not high, and its gangue minerals have little effect on the leaching process and acid consumption of leaching. Although the ore contains copper, the oxidation rate is general, the combination rate is high, the actual leaching rate is low, and the ore contains high iron. (21.9%), not only increase the acid consumption, but also adversely affect the extraction and electrowinning, and also adversely affect the environmental protection of the mine; the ore is highly muddy, the sedimentation rate of the fine mud is slow, and the liquid after leaching Solid separation brings difficulties.
(2) The test results of various schemes, combined with the analysis of the ore properties, indicate that the copper leaching rate and other indicators of the different samples in the small test have achieved the expected results under different conditions in the laboratory. The theoretical (mine sample - 200 mesh accounted for 95.8%) copper leaching rate 54.13%; small particle size (mine sample size -5mm) stirring leaching copper leaching rate 47.51%; large particle size (mine sample size -20mm) groove immersion copper leaching rate 39.26%; column leaching (representing heap leaching) copper leaching rate of 46.34%. The leaching rate of the agitation leaching and the column immersion copper is significantly higher than that of the tank immersion, indicating that the action of air (aerobic) is beneficial to the leaching of copper. The test recommends that the ore leaching process be heap leaching or small particle size (mine sample size -5mm) tank immersion. Under conditions, the tank immersion should consider the frequency and strength of the agitation.
(3) The ore is not suitable for fine-grained leaching (ie, the ore is leached after crushing by ball milling), and is particularly unsuitable for leaching. Due to the serious muddying, the sedimentation time is long, the liquid-solid separation is difficult, and the leaching effect is affected. During the test, some of the fine slime can pass through the filter paper, so in the on-site production, the difficulty of liquid-solid separation should be fully considered. After the ore is crushed and then immersed in the tank, the smaller the particle size, the higher the copper leaching rate, and the granule control is best at -5 mm, and the -200 mesh fine fraction accounts for about 10%.
(4) The ore is more suitable for heap leaching. The leaching speed of the heap immersion copper is faster. Under the same particle size, the copper leaching rate is higher than that of the tank immersion, the acid consumption is low, the iron leaching rate is also low, and the interference caused by the fine mud is also small.
(5) The leaching speed of the ore is fast, the leaching rate reaches 25.65% in 2d, the leaching rate decreases to 0.91g/L on the 9th day, and decreases to 0.68g/t on the 12th, but the copper leaching rate is low, only 46.34%. The combination of copper oxide in the ore is more difficult to leach.
(6) When the ore is leached, the leaching rate of iron is also high. The theoretical (mine sample - 200 mesh accounted for 95.8%) leaching solution iron content 6.75g / L; small particle size (mine sample size -5mm) stirring leaching solution iron content 0.8g / L; large particle size (mine sample size -20mm) tank immersion liquid iron content 1.81g / L; column leaching (mine sample size -20mm) liquid iron content 4.35g / L. In on-site production, the higher concentration of iron in the copper precious liquid (greater than 3g/L) will affect the electrowinning efficiency, increase the power consumption, affect the quality of the copper, and the copper will be lost during the discharge.
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