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Table 1 analysis of iron concentrate composition listed in the iron concentrate, the content of Pb, Zn, Cu and other impurities are 0.29%, 0.36%, 0.32%, the subject requires that the content of Pb in iron concentrate should be reduced to less than 0.1%. The higher the removal rate of other impurities, the better, and the simple screening and washing can not significantly reduce the content of Pb, Zn, Cu, etc. in iron concentrate.
Table 1 Analysis of composition of two-stage magnetic separation-spiral chute iron concentrate (%)
product name | Fe | S | SiO 2 | Pb | Zn | Cu |
Iron concentrate (I+II) | 62.23 | 0.23 | 9.47 | 0.24 | 0.36 | 0.32 |
Since pyrite is generally calcined at a high temperature of 800 to 1000 ° C in the process of acid production, the roasting temperature of Yunfeng Chemical Industry Co., Ltd. in the acid production process is 800-850 ° C. High-temperature roasting causes oxidation of iron in the slag. The structure is dense and the activity is lowered, and the reaction rate with the acid is relatively slow. Therefore, prior to acid leaching, the pyrite slag is first aged with concentrated acid to increase the reactivity of iron oxides in the slag.
The test used the acid leaching effect of H 2 SO 4 , HCl and HF, and the exploratory test of the treatment of pyrite cinder by alkaline leaching with ammonia. If the effect is good, do further tests. If the effect is not good, use other methods. The specific method is as follows: 4 parts of 20 g of slag raw materials and 4 parts of iron concentrate are weighed separately. 6 of them were aged with H 2 SO 4 , HCl, HF for 1 hour, and then the cooked cinder was diluted with dilute H 2 SO 4 , dilute HCl, and dilute HF for 2 hours at a liquid-solid ratio of 1:2; The two parts were directly leached with ammonia water, and the liquid-solid ratio was also 1:2 for 24 hours. After washing with water, drying, weighed and tested. (See Table 2)
Table 2 Exploratory test of acid leaching and ammonia leaching of pyrite cinder
name | Reagent | S (%) | Pb (%) | Cu (%) | Zn (%) |
original Slag | H 2 SO 4 | 2.84 | 0.20 | 0.36 | 0.34 |
HCl | 0.76 | 0.14 | 0.31 | 0.32 | |
HF | 0.41 | 0.10 | 0.26 | 0.29 | |
ammonia | 1.04 | 0.27 | 0.12 | 0.15 | |
iron fine mine | H 2 SO 4 | 0.48 | 0.075 | 0.21 | 0.13 |
HCl | 0.21 | 0.055 | 0.082 | 0.097 | |
HF | 0.19 | 0.058 | 0.093 | 0.11 | |
ammonia | 0.22 | 0.089 | 0.036 | 0.076 |
The results show that all four reagents have obvious effects on the removal of impurities in pyrite cinder. The removal rate of Pb by HCl and HF is relatively high. Relatively speaking, HF has higher removal rate for several impurities, while ammonia leaching has higher leaching rate for Cu and Zn, which can lead to leaching of Cu and Zn. The rate reaches more than 90%; the content of S increases with the slag after leaching with H 2 SO 4 , indicating that it is leached with H 2 SO 4 , one will bring in a part of S, increase the content of S, and the second is likely to be washed. Incompletely, the soluble sulfate in the slag after acid leaching is not washed away, resulting in an increase in the content of S. Since the pyrite cinder is subjected to the above beneficiation process, the particle size is relatively fine, and it is difficult to thoroughly clean the soluble sulfate during the filtration and washing process.
In short, the methods of acid leaching and alkali leaching can effectively remove impurities such as Pb, Zn and Cu in the iron concentrate. A detailed study on the influencing factors of acid leaching (ammonia leaching) removal by different reagents was carried out by orthogonal test. Acid leaching (ammonia leaching) process is shown in Figure 1.
Figure 1 Flow chart of acid leaching and ammonia leaching
I. HCl leaching orthogonal test
The HCl acid leaching was used as a factorial test analysis by three-factor and three-level orthogonal test. The factors and levels of the orthogonal table are shown in Table 3:
Table 3 HCl acid leaching orthogonal test values ​​of each factor
factor | HCl dosage (mL) (A) | Solid-liquid ratio (B) | Leaching time (h) (C) | |
Level | 1 | 3 | 1:1 | 5 |
2 | 5 | 1:1.5 | 10 | |
3 | 8 | 1:2 | twenty four | |
The orthogonal test does not consider the interaction between the various factors. Table 4 shows the design of the orthogonal test head.
Table 4 HCl acid leaching orthogonal test L 9 (3 4 ) head design
Column number | 1(A) | 2(B) | 3(C) | Pb content (%) | |
Test number | 1 | 1 | 1 | 1 | 0.059 |
2 | 1 | 2 | 2 | 0.060 | |
3 | 1 | 3 | 3 | 0.058 | |
4 | 2 | 1 | 2 | 0.054 | |
5 | 2 | 2 | 3 | 0.068 | |
6 | 2 | 3 | 1 | 0.065 | |
7 | 3 | 1 | 3 | 0.059 | |
8 | 3 | 2 | 1 | 0.064 | |
9 | 3 | 3 | 2 | 0.057 | |
∑I 1 | 0.177 | 0.184 | 0.188 | ||
∑I 2 | 0.187 | 0.192 | 0.171 | ||
∑I 3 | 0.180 | 0.180 | 0.185 | ||
Very poor | 0.01 | 0.012 | 0.017 | ||
It can be seen from Table 4 that the extreme difference of the A factor is the smallest, the extreme difference of the B factor is the second, and the extreme difference of the C factor is the largest. The smaller the lead content, the better the index, indicating the influence of the A factor on the lead content. Most notably, the B factor is second, followed by the C factor. The bit level and distribution map of each factor in Figure 2 show that when the A factor is the first level, the obtained index should have the lowest lead content; similarly, B and C are the lead content at the third level and the second level, respectively. The lowest, ie, the ratio of A l B 3 C 2 is a superior test protocol. According to the test results of this condition, the content of lead HCl acid leaching was 0.053%.
Figure 2 HCl acid leaching orthogonal test position and column distribution
Second, HF leaching orthogonal test
Table 5 HF acid immersion orthogonal test value of each factor
factor | HCl dosage (mL) (A) | Solid-liquid ratio (B) | Leaching time (h) (C) | |
Level | 1 | 3 | 1:1 | 5 |
2 | 5 | 1:1.5 | 10 | |
3 | 8 | 1:2 | twenty four | |
Table 5 shows that the extreme difference of the B factor is the smallest, and the extreme difference between the two factors of C and A is the second, indicating that the B factor has the most obvious influence on the lead content, followed by C and A. The bit level and distribution of each factor in Figure 3 show that when the A factor is the first level, the lead content is the lowest; the second level of the B factor is equal to the third level, indicating the second level and the third level. When the equal or similar index can be reached, the second level of the B factor is taken as a small value: the content of lead should be the lowest when C is the third level, that is, the ratio of B 2 C 3 A 1 is a better test scheme. . According to the test results of this condition, the content of lead HF acid leaching was 0.056%.
Table 6 HF acid immersion orthogonal test L 9 (3 4 ) head design
Column number | 1(A) | 2(B) | 3(C) | Pb content (%) | |
Test number | 1 | 1 | 1 | 1 | 0.058 |
2 | 1 | 2 | 2 | 0.062 | |
3 | 1 | 3 | 3 | 0.054 | |
4 | 2 | 1 | 2 | 0.060 | |
5 | 2 | 2 | 3 | 0.056 | |
6 | 2 | 3 | 1 | 0.064 | |
7 | 3 | 1 | 3 | 0.064 | |
8 | 3 | 2 | 1 | 0.060 | |
9 | 3 | 3 | 2 | 0.060 | |
∑I 1 | 0.174 | 0.182 | 0.180 | ||
∑I 2 | 0.180 | 0.178 | 0.182 | ||
∑I 3 | 0.184 | 0.178 | 0.174 | ||
Very poor | 0.01 | 0.004 | 0.008 | ||
Figure 3 HF acid immersion orthogonal test level and column distribution
III. NH 3 ·H 2 O leaching orthogonal test
Table 2 shows that the removal rate of Zn and Cu is relatively high by NH3·H2O ammonia leaching. The following is the ammonia leaching Cu orthogonal test (see Table 7, Table 8).
Table 7 NH3·H2O ammonia immersion orthogonal test
factor | NH3·H2O dosage (mL) (A) | Solid-liquid ratio (B) | Leaching time (h) (C) | |
Level | 1 | 5 | 1:1 | 5 |
2 | 10 | 1:1.5 | 10 | |
3 | 15 | 1:2 | twenty four | |
Table 8 NH3·H2O ammonia immersion orthogonal test L 9 (3 4 ) head design
Column number | 1(A) | 2(B) | 3(C) | Cu content (%) | |
Test number | 1 | 1 | 1 | 1 | 0.036 |
2 | 1 | 2 | 2 | 0.028 | |
3 | 1 | 3 | 3 | 0.031 | |
4 | 2 | 1 | 2 | 0.025 | |
5 | 2 | 2 | 3 | 0.024 | |
6 | 2 | 3 | 1 | 0.033 | |
7 | 3 | 1 | 3 | 0.027 | |
8 | 3 | 2 | 1 | 0.021 | |
9 | 3 | 3 | 2 | 0.029 | |
∑I 1 | 0.095 | 0.088 | 0.090 | ||
∑I 2 | 0.082 | 0.073 | 0.082 | ||
∑I 3 | 0.077 | 0.093 | 0.082 | ||
Very poor | 0.018 | 0.02 | 0.08 | ||
Table 8 shows that the extreme difference of the C factor is the smallest, the extreme difference of the A factor is the second, and the extreme difference of the B factor is the largest. The smaller the copper content, the better the index, indicating that the C factor has the most obvious influence on the lead content. The A factor is second, followed by the B factor. The bit level and distribution of each factor in Figure 4 show that when the A factor is the third level, the copper content is the lowest, the B factor is the second level, and the second and third levels of the C factor are equal and small. The second level is preferred, that is, the ratio of C 2 A 3 B 2 is a superior test protocol. According to the test results of this condition, the content of NH 3 ·H 2 O ammonia immersion copper was 0.023%, and the content of zinc was also reduced to 0.067%.
Figure 4 NH 3 ·H 2 O ammonia immersion orthogonal test level and column distribution
Finally, the removal rate of impurities in iron concentrate is relatively obvious. The content of S was 0.21%, and the contents of Pb, Zn, Cu, and SiO 2 were 0.053%, 0.067%, 0.023%, and 8.26%, respectively. The main components of iron concentrate are shown in Table 9:
Table 9 Composition analysis of iron concentrate
ingredient | Fe | SiO 2 | CaO | S | P | Cu | Zn | Pb |
content(%) | 62.34 | 8.26 | 1.21 | 0.21 | 0.012 | 0.023 | 0.067 | 0.053 |
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