With the rapid development of the iron and steel industry, increasing demand for iron ore resources, a large number of poor iron ore, iron ore tailings, and some intractable have gradually been developed and utilized. The content of iron concentrates produced by these ores is generally high, especially the high sulfur content, which is difficult to meet the quality requirements of iron making and steel making.
Anhui province pyrite ores containing copper 0.3%, sulfur 34.95%, 42.64% iron (magnetic iron 6% to 7%), is a low sulfur copper ore. At present, the mine adopts the process of preferential flotation of copper to produce copper concentrate and sulfur concentrate, and iron is not recovered. In order to improve the comprehensive utilization of resources, consider recycling iron and explore ways to reduce sulfur in iron concentrates.
I. Ore properties and test methods
(1) Raw ore properties
The main minerals in the ore are pyrite, followed by magnetite, pyrrhotite, chalcopyrite, chalcopyrite, limonite, copper blue, malachite, etc., containing a small amount of natural gold and silver . Pyrite is mostly semi-automorphic grain-like aggregates, massive, with a particle size of 0.02 ~ 5mm; chalcopyrite is filled with hemimorphic particles in pyrite or gangue, particle size is 0.01 ~ 1.4mm; other copper ore The material is filled with veins and has a particle size of 0.003 to 0.1 mm. The results of multi-element analysis of raw ore and copper, sulfur and iron phase analysis results are shown in Table 1 and Table 2, respectively.
The useful elements in the mine are mainly sulfur, copper, iron and gold and silver. The copper mineral is mainly copper sulfide, the sulfur mineral is mainly pyrite, a small amount of pyrrhotite, and the recoverable iron mineral is magnetite.
Table 1 Multi-element analysis results of raw ore (mass score) /%
Cu | S | Fe | MgO | CaO | Al 2 O 3 | SiO 2 | Au 1) | Ag 1) |
0.30 | 34.95 | 42.64 | 1.24 | 1.94 | 0.71 | 6.78 | 1.18 | 23.5 |
1) The unit is g/t.
Table 2 Raw mineral phase analysis results
Phase name | Different | content/% | Occupancy rate /% |
Copper phase | Copper sulfide | 0.279 | 93.00 |
Copper in copper oxide | 0.013 | 4.33 | |
Other copper | 0.008 | 2.67 | |
Total copper | 0.30 | 100.00 | |
Sulfur phase | Sulfur in pyrite | 31.89 | 91.24 |
Sulfur in pyrrhotite | 2.59 | 7.41 | |
Sulfur in sulfate | 0.47 | 1.35 | |
Total sulfur | 34.95 | 100.00 | |
Iron phase | Iron in iron oxide | 6.84 | 16.04 |
Ferric oxide | 2.12 | 4.97 | |
Iron in pyrite | 1.97 | 4.62 | |
Other iron in iron sulfide | 29.72 | 69.70 | |
Iron in iron silicate | 0.19 | 0.45 | |
Iron carbonate | 1.80 | 4.22 | |
Total iron | 42.64 | 100.00 |
(2) Test methods
The test ore is a low-copper iron high-sulfur ore. The conventional ore dressing process has two types: first magnetic floating and first floating magnetic. The existing process is limited to the preferential flotation process. Iron concentrate, and then flotation method for iron concentrate desulfurization research.
The individual samples were weighed 500g, firstly milled with XMQ-40×90 cone ball mill, and then floated and magnetically selected by XFD type single tank flotation machine and wet batch high gradient magnetic separator. Agents are used in the test # 2 oil, lime, butyl xanthate, coal oil, sulfate, sulfuric acid, reagents were of analytical grade.
Second, the test results and analysis
(1) First floating magnetic test
According to the actual production situation on site, it is determined that the grinding particle size is -0.074mm, the grain size is 68%, the magnetic field strength is 64kA/m, and the magnetic separation adopts a rough selection process. The test process is shown in Figure 1. The test results are shown in the table. 3.
Table 3 First floating magnetic test results
product name | Yield/% | grade/% | Recovery rate/% | ||||
Cu | S | Fe | Cu | S | Fe | ||
Copper concentrate | 6.63 | 3.78 | 37.55 | 83.24 | 7.13 | ||
Iron concentrate | 12.99 | 0.11 | 9.44 | 63.08 | 4.75 | 3.51 | 19.48 |
Sulfur concentrate | 80.38 | 0.045 | 38.79 | 12.01 | 89.36 | ||
total | 11.00 | 0.30 | 34.90 | 42.06 | 100.00 | 100.00 | |
It can be seen from Table 3 that the process of using the -crude-precision magnetic separation process has a magnetic field strength of 64 kA/m, and the iron concentrate obtained by magnetic separation has a sulfur content of about 9% and a high sulfur content. In order to improve the quality of iron concentrate, desulfurization treatment is required.
(II) Desulfurization test of iron concentrate
1, re-grinding particle size test
In order to determine whether the magnetic iron and pyrrhotite dissociated and the effect of grinding particle size on desulfurization, sulfuric acid was used to adjust the pH value of the slurry to 6.2, copper sulfate activation, kerosene and diphtheria as collectors , and iron concentrate was re-examined. Desulfurization test, the test process is shown in Figure 2, and the test results are shown in Table 4.
Table 4 Results of iron concentrate re-sulphur desulfurization test
Grinding time / min | product name | Yield/% | grade/% | Recovery rate/% | ||
Fe | S | Fe | S | |||
0 | Iron concentrate Desulfurization foam total | 48.72 51.28 100.00 | 65.88 60.93 63.34 | 0.45 16.54 8.70 | 50.67 49.33 100.00 | 2.52 97.48 100.00 |
4 | Iron concentrate Desulfurization foam total | 46.74 53.26 100.00 | 65.95 61.22 63.43 | 0.39 16.70 9.08 | 48.60 51.40 100.00 | 2.01 97.99 100.00 |
8 | Iron concentrate Desulfurization foam total | 46.98 53.02 100.00 | 65.70 60.57 62.58 | 0.32 16.89 9.11 | 49.10 50.99 100.00 | 1.65 98.34 100.00 |
It can be seen from Table 4 that the iron concentrate is no longer desulphurized by the above desulfurization agent conditions. Iron concentrate with 65.88% iron concentrate grade and 0.45% sulfur content can be obtained. The recovery rate of iron operation is 50.67%. After de-sulphurization after re-grinding, the sulfur content of iron concentrate can be reduced to below 0.4%, which is less than slightly lower. The grade and recovery rate of iron concentrates are similar to those of no longer grinding, indicating that re-grinding is beneficial to reduce the sulfur content of iron concentrates. In the test, the sulfur content of the iron concentrate can no longer be reduced to less than 0.5%. Considering the above, the following tests are not re-grinded.
2. pH test of desulfurization operation
The sulfur in the magnetic separation into the iron concentrate is mainly pyrrhotite, which is naturally less buoyant than pyrite, and is inhibited when copper is selected, which is difficult to remove. According to the flow shown in Figure 2, the desulfurization pH value test was carried out under the same conditions of other chemicals and dosages. The test results are shown in Table 5.
Table 5 pH test results
Sulfuric acid dosage / (g·t -1 ) | product name | Yield/% | grade/% | Recovery rate/% | ||
Fe | S | Fe | S | |||
0 (pH=7.0) | Iron concentrate Desulfurization foam total | 79.87 20.13 100.00 | 64.88 55.07 62.91 | 6.44 20.16 9.20 | 82.38 17.62 100.00 | 55.90 44.10 100.00 |
250 (pH=6.7) | Iron concentrate Desulfurization foam total | 68.07 31.93 100.00 | 65.72 57.65 63.14 | 3.04 20.70 8.68 | 70.85 29.15 100.00 | 23.84 76.16 100.00 |
500 (pH=6.2) | Iron concentrate Desulfurization foam total | 48.72 51.28 100.00 | 65.88 60.93 63.34 | 0.45 16.54 8.70 | 50.67 49.33 100.00 | 2.52 97.48 100.00 |
The results in Table 5 show that the pH value is not added with sulfuric acid, only copper sulfate is used for activation. The sulfur in the iron concentrate is poorly floatable, the floating amount is small, and the iron concentrate has high sulfur content. The sulfuric acid is added to adjust the pH value of the slurry. With the increase of the amount of sulfuric acid, the pH value is lowered, the sulfur floatability is better, and the sulfur content of the iron concentrate is lowered. When the amount of sulfuric acid is 500g/t and the pH value is 6.2, the sulfur content of the iron concentrate can be reduced to 0.45%.
3, activator dosage test
Copper sulphate is a commonly used activator for the desulfurization of iron concentrates. The effect of the amount of copper sulfate on the desulfurization effect of iron concentrate was tested. The process flow is shown in Figure 2, pH=6.2, and other chemicals and dosages are fixed. The test results are shown in Table 6.
Table 6 Test results of copper sulfate dosage
Sulfuric acid dosage / (g·t -1 ) | product name | Yield/% | grade/% | Recovery rate/% | ||
Fe | S | Fe | S | |||
0 | Iron concentrate Desulfurization foam total | 88.71 11.29 100.00 | 64.10 55.06 63.08 | 6.93 26.26 9.11 | 90.15 9.85 100.00 | 67.46 32.54 100.00 |
150 | Iron concentrate Desulfurization foam total | 61.17 38.83 100.00 | 65.46 60.18 63.41 | 1.02 20.04 8.41 | 63.15 36.85 100.00 | 7.42 92.58 100.00 |
300 | Iron concentrate Desulfurization foam total | 48.72 51.28 100.00 | 65.88 60.93 63.34 | 0.45 16.54 8.70 | 50.67 49.33 100.00 | 2.52 97.48 100.00 |
The results in Table 6 show that without the addition of activator desulfurization, the iron concentrate contains 6.93% sulfur and the sulfur removal rate is only 32.54%, indicating that the pyrrhotite in the mine is poorly floatable, and the magnetic yellow in the iron concentrate The magnetic floc action of iron ore and magnetite increases the difficulty of removing pyrrhotite, and it is difficult to effectively remove sulfur from iron concentrate by using only the collector. Activated by copper sulfate, the desulfurization effect is obvious. With the increase of the amount of copper sulfate, the sulfur content of iron concentrate decreases. When the amount of copper sulfate is 150g/t, the sulfur content of iron concentrate is 1.02%, and the dosage is 300g/t. The iron concentrate has a sulfur content of 0.45%.
4, collector dosage test
The commonly used collectors for desulfurization of iron concentrates are generally yellow medicines. The production practice proves that the combination of kerosene and xanthate desulfurization is better than single yellow medicine. According to the flow shown in Figure 2, at pH=6.2, when the amount of sulfuric acid steel is 300g/t, the desulfurization collector test is carried out in combination with kerosene and butyl sulphate. The test results are shown in Table 7.
Table 7 Collector dosage test results
Sulfuric acid dosage / (g·t -1 ) | product name | Yield/% | grade/% | Recovery rate/% | ||
Fe | S | Fe | S | |||
Kerosene 40 Ding Huang Yao 100 | Iron concentrate Desulfurization foam total | 52.39 | 65.65 | 0.51 | 54.15 | 3.06 |
47.61 | 61.18 | 17.79 | 45.85 | 96.94 | ||
100.00 | 63.52 | 8.74 | 100.00 | 100.00 | ||
Kerosene 40 Ding Huang Yi 140 | Iron concentrate Desulfurization foam total | 49.93 | 65.43 | 0.46 | 51.76 | 2.54 |
50.07 | 60.81 | 17.58 | 48.24 | 97.46 | ||
100.00 | 63.12 | 9.03 | 100.00 | 100.00 | ||
Kerosene 40 Ding Huang Yao 180 | Iron concentrate Desulfurization foam total | 48.13 | 65.58 | 0.44 | 49.93 | 2.35 |
51.87 | 61.03 | 16.99 | 50.07 | 97.65 | ||
100.00 | 63.22 | 9.02 | 100.00 | 100.00 | ||
The results in Table 7 show that the use of kerosene and Dinghuang as a desulfurization collector can effectively remove sulfur from iron concentrates, but the amount is large. It is suitable to use 4Og/t of kerosene and 100g/t of Dinghuang.
5. Orthogonal test of activator and collector dosage
The production practice shows that the iron concentrate desulfurization activator copper sulfate has a certain interaction with the collector Dinghuang. In order to understand the relationship between the two, the orthogonal test is carried out on the two agents at pH=6.2. The results are shown in Table 8.
Table 8 Orthogonal test results of activator and collector
Sulfuric acid dosage / (g·t -1 ) | product name | Yield/% | grade/% | Recovery rate/% | ||
Fe | S | Fe | S | |||
CuSO 4 200 Kerosene 40 Ding Huang Yao 80 | Iron concentrate Desulfurization foam total | 57.35 | 65.49 | 1.16 | 59.17 | 7.63 |
42.65 | 60.76 | 18.89 | 40.83 | 92.37 | ||
100.00 | 63.47 | 8.72 | 100.00 | 100.00 | ||
CuSO 4 200 Kerosene 40 Ding Huang Yi 140 | Iron concentrate Desulfurization foam total | 54.55 | 65.38 | 0.52 | 56.33 | 3.39 |
45.45 | 60.83 | 17.78 | 43.67 | 96.61 | ||
100 | 63.31 | 8.36 | 100.00 | 100.00 | ||
CuSO 4 200 Kerosene 70 Ding Huang Yi 140 | Iron concentrate Desulfurization foam total | 54.33 | 64.98 | 0.54 | 55.80 | 3.53 |
45.67 | 61.23 | 17.54 | 44.20 | 96.47 | ||
100.00 | 63.27 | 8.30 | 100.00 | 100.00 | ||
CuSO 4 300 Kerosene 40 Ding Huang Yao 80 | Iron concentrate Desulfurization foam total | 53.88 | 65.31 | 0.48 | 55.68 | 3.07 |
46.13 | 60.73 | 17.68 | 44.32 | 96.93 | ||
100.00 | 63.20 | 8.41 | 100.00 | 100.00 | ||
CuSO 4 300 Kerosene 40 Ding Huang Yi 140 | Iron concentrate Desulfurization foam total | 46.92 | 65.99 | O.45 | 49.14 | 2.33 |
53.08 | 60.38 | 16.68 | 50.86 | 97.67 | ||
100.00 | 63.01 | 9.06 | 100.00 | 100.00 | ||
CuSO 4 300 Kerosene 40 Ding Huang Yao 180 | Iron concentrate Desulfurization foam total | 48.13 | 65.58 | 0.44 | 49.93 | 2.35 |
51.87 | 61.03 | 16.99 | 50.07 | 97.65 | ||
100.00 | 63.22 | 9.02 | 100.00 | 100.00 | ||
The results in Table 8 show that in the case of a certain amount of use, when the copper sulfate is too large, the amount of yellow medicine can be reduced, and when the amount of copper sulfate is small, the amount of the yellow rice is required to be used to ensure the desulfurization effect. When sodium sulfate is used at 300g/t and Dinghuang is used at 140g/t and 180g/t, the sulfur content of iron concentrate is 0.45% and 0.44%, respectively, indicating that the dosage of the agent is increased, and it is difficult to significantly reduce the iron concentrate. sulfur. In this test, the amount of copper sulfate is 200-300 g/t, and the dosage of Dinghuang is 80-140 g/t.
(3) Closed circuit test
On the basis of the conditional test, a closed circuit test was carried out. The closed circuit test flow is shown in Fig. 3. The results are shown in Table 9.
The results in Table 9 show that the copper concentrate with 10.98% copper and 77.78% copper recovery, iron concentrate with iron content of 65.38%, sulfur content of 0.84% ​​and iron recovery rate of 11.78% can be obtained by using the first floating magnetic process. The recovery rate of magnetite is 73.44%), the total sulfur concentrate with sulfur content of 37.90% and sulfur recovery rate of 97.82%, the test results are ideal.
Table 9 Closed circuit test results
Copper concentrate | 1.99 | 10.98 | 36.89 | 35.14 | 77.78 | 1.73 | 2.00 |
Desulfurization foam | 5.97 | 0.162 | 60.12 | 23.99 | 3.44 | 8.46 | 4.09 |
Iron concentrate | 7.65 | 0.061 | 65.38 | 0.84 | 1.66 | 11.78 | 0.18 |
Sulfur concentrate | 84.39 | 0.057 | 39.25 | 38.88 | 17.12 | 78.03 | 93.73 |
Total sulfur | 90.36 | 0.064 | 40.63 | 37.90 | 20.56 | 86.49 | 97.82 |
total | 11.00 | 0.28 | 42.45 | 35.01 | 11.00 | 11.00 | 100.00 |
Third, the conclusion
(1) A certain pyrite ore in Anhui Province is a low-copper high-sulfur ore with 0.3% copper, 34.95% sulfur and 42.64% iron. Currently, the copper floatation process is used to produce copper concentrate and sulfur concentrate, and iron is not recovered. The iron concentrate was obtained by the first floating and magnetic method, and the whole process of iron concentrate desulfurization was carried out with 2 # oil as foaming agent, sulfuric acid and copper sulfate as adjusting agent and activator, kerosene and diced yellow as collector. Closed-circuit test can obtain copper concentrate with copper content 10.98% and copper recovery rate of 77.78% and iron concentrate with iron content of 65.38%, sulfur content of 0.84% ​​and iron recovery rate of 11.78%. The effect is ideal.
(2) Sulfuric acid as a regulator is generally added directly in the form of concentrated sulfuric acid, so there is a certain risk. In recent years, a combination of sulfuric acid and copper sulfate has been developed at home and abroad, and has been put into use in similar mine production, and has achieved good indicators. Therefore, it is recommended to carry out the exploration test of the combined agent in the next step.
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