JPS61127833A - Recovery of mercury in iron sulfide concentrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for recovering silver contained in iron sulfide concentrate, and more particularly to a method for recovering silver contained in iron sulfide concentrate by a method other than the back ratio method without phosphatizing the concentrate. Concerning a simple and efficient method of collection.

BACKGROUND OF THE INVENTION One of the sources of silver recovery is iron sulfide. The method of recovering silver from this iron sulfide concentrate has so far relied exclusively on the application of metallurgical means to sulfuric acid burnt ore.
As a result of the narrowing of sales channels for sulfuric acid as a raw material, there is a need to recover silver through other routes.

As a method for leaching gold and silver in ore, ・Thin NaCN
It is very common to use the back ratio method, which performs leaching with a solution, but if the back ratio method is applied when sulfur is present in the ore, 1,000 osyanide ions (-CNS) will be generated in the solution, which will cause leaching. Before applying the leaching method, sulfur must be removed by sifting, flotation, roasting, etc., as this results in waste of the agent and a decrease in the leaching rate. However, since the silver in iron sulfide concentrate is distributed within the iron sulfide mineral itself, it is meaningless to apply desulfurization methods such as selective selection or flotation, and roasting requires a large amount of waste gas treatment. costs. At present, it is difficult to gain public appreciation for the use of comparables. For these reasons, it can be said that the application of the back ratio method to iron sulfide concentrates is no longer considered.

Therefore, there is a demand for the establishment of a new method for recovering silver from iron sulfide concentrates in place of the Sebi method.

11! Therefore, the present inventors conducted repeated studies on leaching agents and treatment processes in order to recover silver from iron sulfide concentrate by a leaching method instead of the back ratio method. Since silver minerals are densely present in iron sulfide concentrate, it is impossible to desulfurize them using normal physical methods.On the other hand, desulfurization by roasting poses problems in terms of cost and waste gas treatment. This is difficult to implement. It has been found that forced oxidation of iron sulfide concentrate in an autoclave is an effective means for separating silver minerals from pyrite. Furthermore, it has been found to be suitable to use thiourea or sodium thiosulfate as a leaching agent for the autoclaved residue in this way. By combining these steps a highly efficient silver leaching process is established.

Thus, the present invention is characterized in that iron sulfide concentrate is forcibly oxidized in an autoclave, filtered, and the residue is leached using thiourea or sodium thiosulfate as a leaching agent. Provided is a method for recovering silver° in iron sulfide concentrate.

The figure is a diagram of the method according to the invention. Iron sulfide concentrates contain varying amounts of silver depending on their source, but for example, iron sulfide concentrates from mines have a FIe of 40 to 5.
0%, 8:45-50%, λgnia 0-150.9/)
It has the composition of

These iron sulfide concentrates are generally D5° (particle size corresponding to 50% of the cumulative distribution curve, with particles larger than and smaller than 1
The grain size is 30 to 50 pmf), but the silver leaching rate can be improved by milling it with a ball mill or the like.

The iron sulfide concentrate is subjected to oxidation treatment in an autoclave after grinding if necessary. In the autoclave, the iron sulfide concentrate is oxidized for a long time in the presence of oxygen and water with stirring. Oxidation conditions vary depending on the autoclave equipment used, the composition of the magnet, the processing amount, etc. Temperature below the melting point of sulfur (113°C), e.g. room temperature to 90°C
At oxygen partial pressure tO~5. It can be implemented under Oatm. A stirring time of 70 to 100 hours is used with sufficient stirring. Through oxidation treatment, pyrite, which is the main component of iron sulfide concentrate, is oxidized and decomposed, and silverite is separated from pyrite.

If autoclaving is performed at a temperature higher than the melting point of sulfur, the autoclaving operation tends to become difficult due to particle agglomeration, so it is preferable to select the treatment temperature as described above.

By leaching the residue after filtration using thiourea or sodium thiosulfate as a leaching agent, thiourea is reduced to approximately 1%.
Silver leaching rates of 0.00% and 80% can be obtained with sodium thiosulfate. This is a much higher value than the conventional method. Although thiourea gives a higher silver leaching rate,
On the other hand, there are disadvantages in that the reagent cost is high and the pH must be kept low. Which leaching agent to select in actual operation is determined based on economic efficiency depending on the target ore.

Leached silver can be easily recovered by conventionally established methods such as electrolytic method or ion exchange method.

Example Iron sulfide concentrate (F@45%, 850%, Ag
Autoclave oxidation and leaching treatments were performed sequentially on 11 Qg/l-on χ.

Each condition is shown in Tables 1 and 2.

Table 1 Autoclave oxidation conditions Iron sulfide refinery @ 45g Water 45 - Temperature 80°C Oxygen partial pressure 2.05 atm Stirring speed
450 rpm Table 2 Leaching conditions and leaching results As can be seen from Table 2, a very high silver leaching rate was obtained. As shown in the comparative example, the silver leaching rate by the assimilation method is about 34% at most, and the rate of increase is remarkable.

NaCN5Jil/ for the same iron sulfide concentrate as in the example.
1 (pH: 1α5) solution for 24 hours.

The silver leaching rate obtained was only 34%.

Reference Example The same iron sulfide concentrate as in Example 1 was directly subjected to thiourea leaching without being subjected to autoclave oxidation treatment. In order to see the effect of Φ ore in a ball mill, the above iron sulfide concentrate was milled in a ball mill, and by changing the milling time, various grain sizes as shown in the table below were obtained:! 4 were made. These iron sulfide concentrates of various particle sizes were leached at 9:00 Ivl using a thiourea solution of 5 moy/l (adjusted to pH=tO with sulfuric acid). The results are shown in the table below.

0 4α0 54.415
29.2 34.750
19, 4 37.1s45
14.6 4! i, 660
14.6 45.5 The silver leaching rate is only about 34%, which is the same level as the assimilation method shown in the comparative example. This shows that the autoclave oxidation treatment plays an important role in improving the silver leaching rate in the present invention. Grain size reduction by grinding appears to provide a 5-10% improvement in silver leaching rate.

Effects of the Invention As an alternative silver recovery method to the assimilation method, it is an efficient method for recovering silver from iron sulfide concentrate that provides a much higher silver leaching rate than the assimilation method and does not require the conventional problems of waste gas countermeasures. The industrial significance of establishing a recovery method is extremely large.

The drawing is a flow diagram of the method of the present invention.

r]

Claims (1)

[Claims] 1) An iron sulfide concentrate characterized by forcibly oxidizing the iron sulfide concentrate in an autoclave, filtering it, and leaching the residue using thiourea or sodium thiosulfate as a leaching agent. How to recover silver.