Multi ocean manganese nodules metal iron-based amorphous or microcrystalline composite oxide ores, mainly iron-rich δ-MnO 2 (also known as ferrous vernadite) and non-crystalline FeOOH · xH 2 O. The average grades of nickel , cobalt , copper and manganese in nodules are 1.30%, 0.22%, 1.00%, 25%. The total amount of corresponding metals in the ocean is tens to thousands of times higher than that of terrestrial metals. This huge metal mineral resource is highly valued by countries. Because nickel, copper, and diamond are embedded in the crystal lattice of iron-manganese minerals in an ion form, smelting extracts valuable metals, and the MnO 2 lattice must be destroyed to release nickel, copper, and diamond. There are mainly industrial application prospects for the treatment of manganese nodules: reduction roasting-ammonia leaching method, high temperature and high pressure sulfuric acid leaching method, smelting-leaching method, cuprous ion-ammonia leaching method and atmospheric pressure hydrochloric acid leaching method. Regardless of the method used, it involves the process of reducing MnO 2 to divalent manganese with a reducing agent, pyrometallurgy using a carbonaceous reducing agent, and hydrometallurgical reducing agents including sulfurous acid and its salts (such as H 2 SO). 3 , SO 2 , Na 2 SO 3 , (NH 4 ) 2 SO 3 , etc.), H 2 O 2 , Fe 2 + salts, and organic chemicals. From the 1970s to the early 1980s, various countries in the world discovered massive seabed massive metal sulfides, which pushed deep sea solid mineral exploration to a new stage. Thermal sulfides and manganese nodules are two redox complementary metal minerals. Consider the idea of ​​the two mining methods to explore the leaching process. However, because hot sulfide is difficult to obtain, according to the data collected so far, there are not many studies on FeS reduction of oceanic manganese nodules. FeS has the advantages of wide source, strong reduction and low price. This paper aims to use the ideas of the two mines. FeS was used as a reducing agent under normal temperature and pressure, and sulfuric acid was used as a leaching agent to explore the feasibility of reducing leaching of Cu, Co and Ni in oceanic manganese nodules under normal pressure, and leaching valuable metals for hot sulfide and manganese nodules. Research is paving the way.

First, the test

(1) Test materials and equipment

The experimental raw materials are the DY105-15 voyage ocean polymetallic manganese nodules in China, the main components are shown in Table 1.

Table 1 Main components (mass fraction) of DY105-15 ocean polymetallic nodules/%

Mn

Fe

P

Cu

Co

Ni

CaO

MgO

Al 2 O 3

SiO 2

29.37

5.19

0.19

1.29

0.15

1.32

1.70

3.0

2.87

15.39

The main experimental reagents are sulfuric acid (purity: 95% to 98%, Institute of Chemical Industry, Zhuzhou City, Hunan Province), ferrous sulfide (purity higher than 80%, Guangdong Taishan Chemical Plant).

The main equipment is: 1000mL beaker, electric mixer, electronic balance, electric dryer.

(2) Test methods

Add 50 g of manganese nodules and a certain amount of FeS to a 1000 mL beaker, pour a certain volume of water, mechanically stir, and add concentrated sulfuric acid. The leaching is completed, hot filtered, washed, dried, and sampled for analysis.

Second, the test results and discussion

(1) Effect of leaching time on leaching rate

Under the condition of manganese nodules mass 50g, FeS addition amount 20g, concentrated sulfuric acid 25mL, liquid-solid ratio 6:1, the influence of leaching time on the leaching rate of Cu, Co, Ni and other metals was investigated. The experimental results are shown in Fig. 1. Shown.

Figure 1 Effect of time on leaching rate

It can be seen from Fig. 1 that the leaching rates of Cu, Co, and Ni are both high in the range of 2-6 h. The leaching rate of iron is below 20%. Finally, the leaching time was chosen to be 4h.

(2) Effect of leaching temperature on leaching rate

Under the condition of manganese nodules mass 50g, FeS addition amount 20g, leaching time 4h, liquid-solid ratio 6:1, concentrated sulfuric acid 25mL, the effect of Wendu on the leaching rate of Cu, Co and Ni was investigated. 2 is shown.

Figure 2 Effect of leaching temperature on leaching rate

It can be seen from Fig. 2 that as the temperature increases, the leaching rate of Cu, Co, and Ni increases, and the reaction is carried out under normal pressure to finally determine the optimum temperature.

It is 95 ° C.

(3) Effect of sulfuric acid dosage on leaching rate

Under the condition of manganese nodules mass 50g, FeS addition amount 20g, leaching time 4h, liquid-solid ratio 6:1, the effect of sulfuric acid dosage on Cu, Co and Ni leaching rate was investigated. The experimental results are shown in Fig. 3.

Figure 3 Effect of sulfuric acid dosage on leaching rate

It can be seen from Fig. 3 that the amount of sulfuric acid has a great influence on the reaction. When the amount of sulfuric acid is 15 mL, only a small amount of Cu, Co, and Ni are leached, indicating that the amount of acid is insufficient. As the amount of sulfuric acid gradually increased to 40 mL, the leaching rates of Cu, Co, and Ni all reached 95%, but the leaching rate of total Fe increased to 27.65%. Considering that iron was removed in the subsequent treatment, it was finally determined that the amount of sulfuric acid added was 35 mL.

(4) Effect of FeS dosage on leaching rate

Under the condition of manganese nodules mass 50g, concentrated sulfuric acid 35mL, leaching time 4h, leaching temperature 95 °C, liquid-solid ratio 6:1, the effect of FeS dosage on Cu, Co and Ni leaching rate was investigated. Figure 4 shows.

Figure 4 Effect of FeS dosage on leaching process

The amount of FeS has a great influence on the leaching rate of Cu, Co and Ni. When the amount of FeS increases to 20g, the leaching rate of Cu, Co and Ni gradually increases to over 95%. The leaching rate of Co and Ni decreased with the increase of FeS dosage to 30g. The leaching rate of Cu decreased most obviously, and the leaching rate of Fe also reached 35.81%. The reason may be Cu, Co, Ni sulfide precipitation. Therefore, in order to reduce the burden of subsequent separation and removal of iron, the optimum amount of FeS should be controlled at 20g.

(5) Effect of liquid-solid ratio on leaching process

Under the condition of manganese nodules mass 50g, FeS addition amount 20g, concentrated sulfuric acid 35mL, leaching time 4h, leaching temperature 95 °C, the influence of liquid-solid ratio on the leaching rate of Cu, Co and Ni was investigated. Figure 5 shows.

Figure 5 Effect of liquid-solid ratio on leaching process

The liquid-solid ratio has a certain influence on the leaching process. When the liquid-solid ratio exceeds 6:1, the leaching rate does not change much, so the liquid-solid ratio is finally determined to be 6:1.

(6) Comprehensive experimental results

On the basis of the conditional experiment, the optimal leaching conditions were as follows: manganese nodules had a mass of 50 g, FeS was added in an amount of 20 g, concentrated sulfuric acid was 35 mL, leaching temperature was 95 ° C, liquid-solid ratio was 6:1, and leaching time was 4 h.

Comprehensive experiments were carried out under these conditions. The experimental results show that the leaching rates of Cu, Co and Ni can reach: 95.58%, 99.61% and 98.74%, respectively. At the same time, the leaching rate of Mn was 98.60%, and the leaching rate of total iron was 25.54%.

Third, the conclusion

(1) Using FeS as a reducing agent and sulfuric acid as a leaching agent, Cu, Co and Ni in oceanic manganese nodules can be leached under normal pressure conditions.

(2) The leaching optimization conditions are: manganese nodules have a mass of 50 g, FeS is added in an amount of 20 g, concentrated sulfuric acid is 35 mL, leaching temperature is 95 ° C, liquid-solid ratio is 6:1, and leaching time is 4 h. Under these conditions, the leaching rates of Cu, Co and Ni can reach: 95.58%, 99.61% and 98.74%, respectively. At the same time, the leaching rate of Mn was 98.60%, and the leaching rate of total iron was 25.54%. This study laid a good foundation for the efficient leaching of valuable metals by hot sulfide and manganese nodules.

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