Indium is one scattered metal content in the crust is very low, no separate indium deposits, primarily enriched in sulphide ores, in particular the sphalerite, zinc smelting, lead byproducts.

The separation and extraction methods of indium include leaching resin separation, liquid membrane separation, solvent extraction, etc., and solvent extraction has been widely used in industry. P204 and P507 are commonly used extractants in industry. P204 has the characteristics of high stripping acidity, easy aging of extractant, poor recycling ability and easy emulsification during extraction. P507 can be used as an extractant of indium instead of P204 to overcome these shortcomings. .

In this paper, soft manganese oxide ore leaching of zinc concentrate, and extracted with P507 indium iron separation, wherein the divalent metal little interference, interference is the greatest, iron and indium have similar properties, the most difficult to be separated from coexisting impurities. Therefore, the separation of indium and iron is the key to recovering indium.

First, the experimental part

Test materials: pyrolusite (containing 30% manganese dioxide) and zinc concentrate, main components of zinc concentrate: Zn 48%, Fe 36%, Pb 2.7%, Cu 0.55%, In 55 g/t, Ag 26g/ t.

Experimental equipment: HY-4 type speed regulation multi-purpose oscillator; DKZ-2 type electric heating constant temperature oscillation water tank; DHG-9023A type electric heating constant temperature air drying oven.

Reagents: P507, sulfonated coal oil, potassium hydrogen phthalate, calcium carbonate as the base reagent, other reagents were of analytical grade.

Washing conditions: room temperature, equilibration time 5 min, compared to O/A = 2/1.

Determination of washing rate: washing rate %=∑[Y] _A /∑[Y] _O

Where: [Y] _A is the washing water phase Y concentration, and [Y] _O is the loading organic phase Y concentration.

Second, the experimental results and discussion

(1) Effect of equilibrium aqueous phase acidity on P507 extraction of indium and iron

The fixed temperature is 293K, compared with O/A=1/1, the oscillation time is 10min, and the standing time is 5min (if the following extraction conditions are not specified), the results of extracting indium and iron under different acidity conditions are shown in the table. As shown in Table 1, it can be seen from Table 1 that the extraction rate of indium and iron increases with the decrease of acidity. Considering the enrichment of indium in the organic phase and the washing of the supported organic phase, it is appropriate to select the acidity of the aqueous phase of 1.5 mol/L. At this time, the iron extraction rate is not higher than 20%.

Table 1 Effect of acidity on extraction rate

(2) Effect of volume concentration of leather extract on indium and iron extraction

The volume concentration of the extractant P507 in the organic phase was 10%, 20%, 30%, 40%, 50%, 60%, respectively.

The results are shown in Fig. 1. As can be seen from Fig. 1, as the volume concentration of P507 increases, the extraction rate of indium and iron increases significantly, and when the concentration of P507 is greater than 30%, the curve gradually becomes gentle, plus The concentration of the large extractant and the change of the extraction rate are no longer obvious. It can be seen that 30% of P507 can extract most of the indium, and the first-order extraction rate is 99.95%. At this time, the first-order extraction rate of iron is 16%. Based on various factors, the optimal volume concentration of the extractant is determined to be 30. %.

(III) Effect of temperature on the extraction of indium and iron

Temperature is also one of the key factors affecting the extraction of indium. Theoretical analysis of the extraction reaction is an exothermic reaction, the temperature rise is not conducive to the forward progress of the extraction reaction, the general extraction is carried out at room temperature, but when the temperature of the solution is too low, the organic phase extraction activity will decrease, the organic phase When the water phase is in contact with the water, the water phase is sticky, and a water-in-oil type third phase is severely generated, resulting in emulsification and slowing down the diffusion rate of the molecules.

Therefore, a certain temperature must be ensured during the extraction process, but the temperature should not be too high, otherwise the organic phase will be volatilized, resulting in loss of the organic phase. The results in Figure 2 indicate that 293K is the best condition.

(4) The effect of extracting indium and iron from P507

The effect of different indium on the extraction of indium iron, as shown in Figure 3, with the increase of the ratio, the extraction rate of indium and iron increases and decreases, when the ratio is 1..1, the extraction rate of indium is greater than 99%, while the extraction rate of iron is only 16%, the separation factor is the largest, so the comparison is 1..1.

(5) Effect of equilibrium time on extraction rate

The effect of time on the extraction rate of indium and iron is shown in Fig. 4. There is no emulsification in the extraction process, and it is easy to stratify. The kinetic reaction speed of extracting indium is fast. According to the analysis of Fig. 4, the extraction rates of indium and iron increase with time. At 9 min, the indium extraction rate was 99.53%, and the iron extraction rate was 16.30%, so 10 min was the best.

(6) Washing and stripping of the loaded organic phase

The supported organic phase was washed with 30 g/L of oxalic acid, the In washing rate was 0.000 1%, and the Fe washing rate was 99.99%. It is indicated that in the leaching solution of oxidized leaching of sphalerite with pyrolusite, the washed iron hardly interferes with the extraction and recovery of hydrazine.

Third, the conclusion

The indium-containing leachate was extracted with 30% P507+70% sulfonated kerosene. The first-order extraction rate of indium was up to O/A=1/1, acidity 1.5mo1/L, extraction time 10min, temperature 293K. More than 20%, the extraction rate of iron is below 20%. After washing with oxalic acid, the washing rate of iron is 99.99%, which can meet the purpose of enrichment and separation of valuable metal indium.

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