JPH10251771A - Nickel leaching method from nickel-containing sulfide ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To profitably recover nickel from a low-grade nickel-contg. sulfide ore which is not payable by the conventional method by suspending the ore in an acidic aq. soln., inoculating sulfur oxidizing bacteria and leaching nickel into the soln. SOLUTION: A low-grade nickel-contg. sulfide ore such as tailings are suspended in an aq. soln. acidified with sulfuric acid. Cultured sulfur oxidizing bacteria are inoculated, air is fed into the soln. by vibration and stirring while keeping the soln. at a temp. optimum for the growth of the bacteria and nickel is leached as ions into the soln. and recovered, e.g. by extraction and electrowinning. Thiobacillus thiooxidans is preferably used as the sulfur oxidizing bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for leaching nickel using sulfur-sulfurizing bacteria to recover nickel from nickel-containing sulfide ores.

[0002]

2. Description of the Related Art In recent years, a method of leaching and recovering copper using a method such as dump leaching or heap leaching in which copper ore is sprayed with sulfuric acid or the like to recover a copper leaching solution has spread worldwide and has become a major copper recovery method. It is occupying the ratio. In such a leaching method, it is considered that microorganisms such as iron oxidizing bacteria inhabiting the ore promote leaching of valuables, and various studies have been continuously made on this.

[0003] Iron-containing nickel sulfide minerals are also subject to the above-mentioned microbiological leaching, and various leaching methods have been studied. However, experiments on a pilot plant scale have not been carried out, and it is said that there is a problem in economics. .

[0004] By the way, usually, flotation tailings of flotation tailings and the like after flotation of sulfide ores and recovery of valuable materials as sulfide concentrates contain valuable metals in various grades. Is well known. In order to recover these metals in flotation tailings as concentrates, there are methods such as applying a physical separation method such as flotation or elution into a solution by adding an acid or oxidizing agent. It is conceivable that the profitability of any of these methods is not sufficient with the grade of valuable metal contained in the waste, and therefore, the actual situation is that the waste is directly discarded.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for recovering nickel by economically leaching nickel from low-grade nickel-containing sulfide ore, which is not profitable with conventional methods. That is.

[0006]

According to the present invention, there is provided a method for suspending a nickel-containing sulfide ore in an aqueous solution.
The present invention is characterized by a nickel leaching method in which nickel is leached into the aqueous solution by inoculating a sulfur-oxidizing bacterium.

That is, in the present invention, after suspending a low-grade nickel-containing sulfide ore such as nickel flotation tailing or the like in a sulfuric acid aqueous solution, inoculating a sulfur-oxidizing bacterium which has been cultured in advance,
While maintaining the optimal temperature for the growth of the inoculated bacteria,
Air is supplied to the aqueous solution by stirring, and nickel is leached into the aqueous solution as ions to recover nickel. The sulfur-oxidizing bacteria used in the method of the present invention include Thiobacillus thiooxydans (Thiobac).
It is preferable to use illus thiooxidans). In recovering nickel from the leachate obtained by the method of the present invention, there is a method of extracting with a solvent and performing electrolytic sampling.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention comprises the steps of suspending a fine-grained, low-grade nickel-containing sulfide ore in a sulfuric acid acidic aqueous solution having the composition shown in Table 1 below and then culturing the sulfur-containing solution. Thiobacillus thiooxidans, an oxidizing bacterium (T
(Hiobacillus thiooxidans) was inoculated at a sufficient cell concentration, and air was supplied to the aqueous solution by shaking and stirring while maintaining the optimum temperature for the growth of the inoculated bacteria, and nickel was leached into the aqueous solution as ions. Nickel is leached into the liquid.

[0009]

[Table 1]

[0010] The nickel-containing sulfide ore used in the present invention generally has a higher nickel leaching amount as the particle size is smaller. It is economically advantageous.

The sulfur-oxidizing bacterium used in the present invention, Thiobacillus thiooxydans (Thiobacillus).
thiooxidans) oxidize sulfur to sulfuric acid according to the following reaction formula. 2S + 3O ₂ + 2H ₂ O → 2Η ₂ SO _{4 The} produced sulfuric acid is consumed for leaching of minerals, that is, for leaching of nickel.

[0012]

Next, examples of the present invention will be described below together with comparative examples. After culturing in a medium in which 1% of powdered sulfur was added to the aqueous solution having the composition shown in Table 1 above, and after completion of logarithmic growth (cell concentration of 10 ⁸ to 10 ⁹ cells / milliliter), Thiobacillus thiooxidans was measured. The contained aqueous solution was prepared.

On the other hand, 10.0 g of a nickel-containing sulfide ore shown in Table 2 below obtained by flotation of nickel-copper ore and 150 ml of an aqueous solution having the composition shown in Table 1 above were mixed with 3
In a Erlenmeyer flask having a capacity of 00 ml, about 1 ml of the aqueous solution containing Thiobacillus thiooxydans prepared in advance as described above was inoculated into the Erlenmeyer flask, and rotated and shaken at 30 ° C. and 128 rpm for 3 weeks. Stirring was performed.

[0014]

[Table 2]

As a result, after 3 weeks, the concentration of nickel eluted in the aqueous solution was 78 ppm. −
On the other hand, the nickel concentration under the same conditions as in the above test without inoculating Thiobacillus thiooxydans was 4%.
It was 9 ppm, and the amount of nickel leached was increased about 1.6 times by inoculation of Thiobacillus thiooxidans. Table 3 shows the results of the above leaching test. After 3 weeks, the leaching rate of nickel was 33% when no bacteria were inoculated, and 53% when inoculated.

[0016]

[Table 3]

[0017]

As described above, according to the method of the present invention,
Since the leaching rate of nickel can be easily increased, it is possible to recover nickel at low cost if applied to low-grade nickel-containing sulfide ores.

Claims (1)

[Claims] 1. A nickel leaching method comprising suspending a nickel-containing sulfide ore in an aqueous solution, inoculating a sulfur-oxidizing bacterium, and leaching nickel into the aqueous solution.