Experiment on extraction of copper from bioleaching solution containing copper and iron

With the advancement of science and technology and the development of the economy, the demand for copper products at home and abroad is growing. However, the rich ore and easy mining in copper mines around the world are gradually decreasing, and people's awareness of environmental protection is gradually increasing, which has led to increasing difficulties in pyrometallurgical copper. Since the 1980s, the development of new high-efficiency extractants has led to the development of copper “leaching-extraction-electrowinning” technology. The technology has the advantages of simple process, low investment, low cost, good environmental protection and high product quality, especially for dealing with complex low-grade ore. The past 20 years, the technology has been widely applied in the field of hydrometallurgical copper. At present, copper produced by this technology accounts for about 25% of the world's total copper, and the proportion is still rising.

Professor Qiu Guan scientifically proposed to use the "bioleaching-extraction-electrowinning" process to prepare high-purity copper for comprehensive recycling of copper. The extraction process uses Lix984 as an extractant. Lix984 is a volume ratio of 1 Lix860 (aldoxime) and (oxime) was Lix62 high flash point of kerosene. This mixture has a synergistic effect, combined with the extraction ability and kinetics of aldoxime, excellent back extraction and physical properties of ketone oxime. The active substance is 2-hydroxy-5-mercaptoacetylacetonone and 2-hydroxy-5-dodecyl salicylaldoxime. The extraction reaction functional group in the structural formula is hydroxyl group (-OH), mercapto group (=N-OH). . The basic reaction for extracting copper is:

Cu ^{2 +} +2HR=CuR ₂ +2H ⁺ (1)

Cu ^{2 +} +4HR=CuR ₂ +2HR+2H ⁺ (2)

In recent years, there have been many research reports on copper solvent extraction, and the extractant Lix984 has been widely used because of its high-efficiency separation of copper. Considering that the electrowinning production process in the sulfuric acid medium is mature and the site state is stable, the sulfuric acid solution is used for back extraction, and the back extraction test conditions are stable and mature, so this article will not discuss. However, iron has a great influence on the extraction process and electrodeposition process, and even leads to serious emulsification. This paper mainly studies the selective extraction of copper from the copper-containing and ferric acid leaching solution obtained from the leaching of low-grade copper ore from a mine. The effects of various factors on the extraction of copper and iron were investigated.

First, the experiment

(1) Experimental materials

The raw material used in this experiment was a bioleaching solution of a copper mine in Jiangxi. The mass ratio of copper/iron in the solution was 1:2.04, and the composition thereof is shown in Table 1.

Table 1 Bioleaching composition / (mg · L ^{- 1} )

The extractant used in the test is Lix984 industrial product produced by Henkel Company of Germany; the diluent is laboratory-made sulfonated kerosene; the stripping agent is laboratory-formed sulfuric acid solution; the pH value is adjusted with dilute sulfuric acid or dilute NaOH solution; The water is deionized water.

(2) Experimental methods

The experiment was carried out in a 250 mL separatory funnel. The organic phase and the aqueous phase are added to the separatory funnel in a certain ratio, and if necessary, the pH value of the solution is adjusted with dilute sulfuric acid or sodium hydroxide, and the mixture is shaken on the shaker to a preset time, and then layered at rest. The raffinate (aqueous phase) was analyzed for the concentration of copper and iron ions by an atomic absorption spectrometer (Beijing Ruili Analytical Instruments Co., Ltd.) to calculate the extraction ratio, the distribution ratio, and the partition coefficient.

The extraction rate η _Me refers to the concentration of the extract (Me); C is the concentration of the extract (Me) after solution extraction.

The distribution ratio D _Me refers to the distribution of the extracted material in the two phases when the equilibrium is extracted, that is, the ratio of the amount of the extract in the organic phase to the amount of the extract in the aqueous phase. The larger the distribution ratio, the more easily the extract is extracted into the organic phase.

The separation factor β _{A / B} is also called the distribution factor, which is a physical quantity indicating the degree of separation between substances, which is equal to the ratio of the distribution ratio of the two substances in the same extraction system under the same extraction conditions.

(4)

D _A and D _B represent the extraction-distribution ratio of the two substances. Generally, A represents the easily extractable component Cu, B represents the difficult-to-extract component Fe, and β _{A / B} indicates that the transfer of A and B substances from the aqueous phase to the organic phase is difficult. The difference in the degree of easiness, the larger the β _{A / B} , indicates that the easier separation of the two substances, the better the selectivity of the extraction.

Second, the results and discussion

(1) Effect of pH on extraction

The pH of the bioleaching solution with pH 2.22 was adjusted to 1.0, 1.5 and 2.5 with dilute sulfuric acid and sodium hydroxide, respectively, and the pH of the leachate was determined after extraction for 4 min at 200 r/min at a normal temperature of 1:1. The effects of iron extraction rate, distribution ratio, and separation factor are shown in Figures 1-3, respectively.

Fig.1 Effect of pH on extraction rate of Cu and Fe

It can be seen from Fig. 1 that the pH value of the bioleaching solution has little effect on the extraction rate of copper, but has a great influence on the extraction rate of iron. With the increase of pH value, the extraction rate of iron has a tendency to decrease, especially at pH=2.5, the leaching rate suddenly drops significantly.

Fig. 2 Effect of pH on the distribution ratio of Cu and Fe

It can be seen from Fig. 2 that in this extraction system, the distribution ratio of iron is small, indicating that only a small amount of iron in the aqueous phase enters the organic phase and does not change greatly with pH. The distribution of copper is much larger than that of iron, indicating that copper and iron can be separated very well. The distribution ratio of copper is maximum near pH 2.22, and the separation coefficient is also maximum. When pH=2.2, Conducive to the separation of copper and iron from bioleaching.

Figure 3 Effect of separation factor on pH

It can be seen from Fig. 3 that as the pH value increases, the partition coefficient increases, and the increase is obvious at pH value of 2.2. When pH=2.5, the partition coefficient reaches the maximum, further indicating that at pH=2.5, copper, The separation coefficient of iron is the largest, reaching 1924 times. It can be seen that the copper and iron in the bioleaching solution can achieve a good separation effect.

(2) The initial concentration and the effect on the extraction

When the initial concentration of copper and iron in the leachate is changed by mass ratio (Cu/Fe=1/2.04), the pH of the leachate is 2.2, and the extraction is carried out at 200 r/min for 4 min. The change is compared with the initial concentration of different copper and iron in the bioleaching solution. The effects on the extraction rate, the distribution ratio, and the separation factor are shown in Figures 4-6, respectively.

Figure 4 compares the effect on extraction rate

1- 10g/L Cu, 20.4g/L Fe; 2-5g/L Cu, 10.2g/L Fe; 3-1g/L Cu, 2.04g/L Fe;

It can be seen from Fig. 4 that with the decrease of the initial concentration of copper and iron in the solution, the extraction rate of copper and iron increases, and the extraction rate of copper increases obviously. When the initial concentration of copper decreases from 10g/L to 1g/L, the extraction rate of copper decreases. It has increased by more than 40%, but the extraction rate of iron has only increased by about 15%. When the initial copper-iron concentration is constant, the extraction rate of copper increases significantly as the ratio increases, increasing from 1/3 to 3 compared to O/A. The extraction rate of copper can be increased by 30% to 47%, while the extraction rate of iron is not significantly changed. It can be seen that the lower the initial concentration of copper, the better the extraction of copper. No matter how high the initial concentration of copper and iron is, the increase is beneficial to copper extraction.

Figure 5 shows the effect of copper-iron distribution ratio

Figure 6 compares the effect on the separation coefficient of copper and iron

It can be seen from Fig. 5 that as the initial concentration of the leachate decreases, the copper distribution ratio increases significantly. When the ratio is 3, the initial copper concentration decreases from 10 g/L to 1 g/L, and the copper distribution ratio increases from 1.1 to 12, increased by nearly 20 times, and when the ratio is 1, the initial concentration of copper is reduced from 10g / L to 1g / L, and the distribution ratio of copper is increased from 0.8 to 21. It can be seen that copper in the low concentration copper solution is easily extracted into the organic phase. From the separation coefficient of copper and iron in Fig. 6, the separation coefficient of copper and iron increases obviously with the decrease of the initial concentration of the leachate; with the increase of O/A, the initial copper concentration is 10g/L and 5g/L. The separation coefficient of copper and iron in the solution increased. For the solution with initial copper concentration of 1g/L, the separation coefficient of copper and iron increased firstly with the increase of O/A ratio, and the maximum O/A ratio reached 1:1, reaching 34. Then lower, the reason for further research.

(3) Effect of temperature and stirring speed on extraction

Further investigate the extraction and separation effect of copper and iron in the extractant Lix984. The concentration of copper and iron in the bioleaching solution was prepared to be 10 and 20.4 g/L according to the ratio of the bioleaching solution, and the O/A ratio was 1:1 and the temperature was 30 °C. The stirring time at 40 ° C was 4 min, and the stirring speed was changed. The extraction ratio, the distribution ratio and the separation coefficient are shown in Figures 7-9, respectively.

Figure 7 Effect of stirring speed on extraction rate of copper and iron

Figure 8 Effect of stirring speed on the distribution ratio of copper and iron

Fig. 9 Effect of stirring speed on separation coefficient of copper and iron

From the kinetic point of view, the stirring speed is large, which is beneficial to the contact frequency of the metal phase liquid droplets with the metal ions in the inorganic water phase, so that the two liquid phases are uniformly mixed, and the reactor is in an ideal full-mix state, so that the liquid is sufficiently maintained. The turbulent state is conducive to the progress of the extraction reaction. The experimental results from Fig. 7 show that the stirring speed has little effect on the extraction of iron. When the stirring speed is from 120r/min, the copper extraction rate is 25%, and suddenly increases to 200 r/min. The effect of the rotation speed on the extraction rate is not obvious. It is stated that the external diffusion is not a control step of the process when the rotational speed is greater than 200 r/min. Therefore, the selected stirring speed is preferably 200-250 r/min.

It can be seen from Fig. 7 that the extraction rates of copper and iron at 30 ° C and 40 ° C have not changed much, and the extraction rate of copper at 40 ° C is slightly higher than the extraction rate of copper at 30 ° C.

Figure 8 and Figure 9 also show that the stirring speed is increased, copper is more easily extracted into the organic phase, and the distribution of iron is relatively low. Copper is more easily extracted into the organic phase, and the distribution of iron is lower, less than 1 It indicates that iron is difficult to react with Lix984 extractant and enters the organic phase, resulting in a separation coefficient of copper and iron reaching 30 or more at 40 °C. As the temperature increases, as the stirring speed increases, the increase in the separation coefficient of copper and iron is more pronounced.

(4) Effect of stirring time on extraction

When the concentration of copper and iron in the initial leachate is changed by mass ratio (Cu/Fe=1/2.04), the pH of the leachate is 2.2, and it is extracted at room temperature at 200 r/min. The mixing time is changed to 1:1. The effects of stirring time on the extraction rate, partition ratio and separation coefficient of different initial concentrations of copper and iron in the leachate are shown in Figures 10-12.

Figure 10 Effect of stirring time on extraction rate of copper and iron

Figure 11 Effect of stirring time on the distribution ratio of copper and iron

Figure 12 Effect of stirring time on the separation coefficient of copper and iron

It can be seen from Fig. 10 that when the initial copper concentration is 10g/L, the copper extraction rate increases with the extension of the stirring time. After stirring for 1min, the copper extraction rate is 35%. After 8 minutes, the copper extraction rate is increased to 60%. , increased by 25%, and when the initial copper concentration is 5g / L, 1g / L, the copper extraction rate increased by 30%, 40%; and the iron extraction rate did not change significantly with the stirring time.

It can be seen from Fig. 11 and Fig. 12 that as the stirring time is extended, the distribution ratio of copper increases, the separation coefficient increases, and the iron does not change significantly, and the separation coefficient of copper and iron increases.

(5) Effect of extraction series on extraction

The bioleaching solution with a pH of 2.22 was compared with 1:1, and after extraction at 200 r/min for 4 min, the relationship between the extraction grade and the extraction ratio, distribution ratio and partition coefficient of copper and iron was as shown in Fig. 13-15. Show.

Figure 13 Effect of extraction series on extraction rate

Figure 14 Effect of extraction series on distribution ratio

Figure 15 Effect of separation factor on extraction rate

It can be seen from Figures 13 to 15 that as the number of extraction stages increases, the amount of adsorption of the extractant increases, the adsorption capacity decreases, and the extraction rate decreases. In contrast, as the number of extraction stages increases, the extraction rate of iron decreases more severely. The distribution ratio of iron is close to zero, and the distribution ratio of copper is relatively high. The distribution ratio of copper in the vicinity of the extraction level of 3 is maximized. When the extraction order is about 3 and the partition coefficient is maximized, the separation effect of copper and iron is the best. After the extraction series is greater than 3, the distribution coefficient decreases as the number of extraction stages increases. It is further explained that while the adsorption amount of the extracting agent is increasing, the adsorption capacity is continuously decreased, and the extraction ability is decreased.

Third, the conclusion

By extracting the bioleaching solution with Lix984, copper was selectively extracted from the copper-iron-containing bioleaching solution, and the pH value of the solution, O/A, initial copper concentration, extraction temperature, stirring speed and stirring time, and extraction grade were investigated. The influence of several factors on the extraction rate, partition ratio and separation coefficient showed that the pH value was greater than 2.22, compared with O/A=1:1, the stirring speed was 200 r/min, the stirring time was 4 min, and the extraction series was At the third level, the extraction rate of copper can reach above 99.8%, the copper distribution ratio can reach 600 or more, the iron distribution ratio is less than 1, and the separation coefficient of copper and iron can reach 1900 or more. Meanwhile, it is found that low initial copper concentration and high extraction temperature are favorable for extraction. It can be seen that copper and iron in the bioleaching solution can achieve a good separation effect.

 In strict accordance with ISO 9001:20015 and EN Flanges;
    1.Make process card and quality plan
    2.Choose the qualified raw material and do incoming test, not allowed      
     nonconforming material to enter into production process;
    3.Producing and testing followed the quality documents 
    4.Be good at Quality records and product identification to ensure the product 
    traceability
    5.Do the final inspection to ensure 100% of pass.

En Flanges

En Flanges,En 1092 Flange ,En Flange Stainless,High Quality En Flanges

Shanxi Tianbao Group Co.,Ltd. , https://www.tbflange.com