Method of determination of gold and silver content in sulphide ores and products of their processing

FIELD: metallurgy.

SUBSTANCE: proposed method comprises annealing of initial charge, selective leaching and analytical determination of noble metal content in produced solution. Charge annealing is performed in microwave frequency field without access of air at 550-600C Annealed product is leached in steps by adding successive volumes of thiourea sulphide solution. Content of noble metal in obtained solutions is analytically defined to sum obtained values for determination of noble metal content in initial charge.

EFFECT: higher validity of estimation.

2 cl, 1 tbl, 2 ex

 

The invention relates to the field of analytical chemistry of the noble metals, and can be used to determine the gold, silver and platinum group metals in sulfide ores and products of their processing.

The known method of assay concentration of gold and platinum group metals in the copper-Nickel collector developed for the analysis of sulfide copper-Nickel ores [Danilov PI, IGOR Fedotov, Nazarenko, R.M. Assay-chemical-spectral determination of platinum group metals and gold in sulfide copper-Nickel ores and products of their processing. Laboratory, 1982, 48, 8, p.9-10.]. The known method includes oxidizing roasting weighed samples of the ore at a temperature of 850C for 7 hours, mixing the calcine with copper oxide (CuO), sodium carbonate, sodium tetraborate, sodium silicate glass and starch, crucible, melting the mixture at 1200C with obtaining slag and copper-Nickel alloy, followed by dissolving the alloy in hydrochloric acid, the sorption of noble metals from solution on activated carbon and the sorbent PVB-MP-20T, quantitative determination of their content atomic emission method.

The disadvantages of this method include the high cost, due to oxidative roasting of a sample of ore sample and dissolution of the entire mass of copper-Nickel alloy obtained PR the crucible smelting. In this case, if the content of the studied metals slightly, it is impossible to ensure the accuracy of the quantitative analysis due to the heterogeneity of the distribution of metals in ores that are difficult to take into account when taking the sample the sample for analysis.

There is also known a method of analysis of noble metals, in which a portion of the sample analyzed material is subjected to pre-treatment - burning or leaching in acid order decomposition of sulphides and removal of non-ferrous metals, the residue from the digestion of the sample is mixed with lead oxide, sodium carbonate, silicate glass, sodium tetraborate, sodium nitrate or potassium, calcium oxide, nitrate or chloride of silver, and the carbonaceous reducing agent to obtain a mixture, the mixture is melted at a temperature of 1100-1300C with obtaining slag and lead alloy - free. The products of melting share, free kapelrud to silver or gold-silver goldcrest [Probootborniki and analysis of noble metals, Ed. by Baryshnikov IVAN - M.: metallurgy, 1968, p.131-134, 151-158, 316-320]. The content of noble metals in the Wren determine chemical and physico-chemical methods.

The disadvantage of this method are the high costs associated with conducting operations pre-treatment sample sample analyzed material before probem is th fuse. In addition, when a low content of noble metals, the known method does not allow to ensure the accuracy of quantitative analysis.

Closest to the proposed method is preliminary roasting of sulfide ores and their processing products containing gold and silver assay in the analysis, including the oxidation of ores oxygen in fireclay boats in a muffle furnace at two modes of firing, and the firing starts at 250-300C and finished at a temperature of 450-500C for 10-15 min the incomplete removal of sulfur [patent RU No. 2224805, IPC C22B 11/02, 2004].

The main disadvantage is the large values of error due to the microinhomogeneity of samples and technical limitations of sample handling large mass to minimize the impact of heterogeneity.

The objective of the invention is to increase the reliability of determination of gold and silver in sulfide ores and products of their processing.

The problem is solved in that the proposed method of determination of gold and silver in sulfide ores and products of their processing, which includes the firing of the original sample with the subsequent election of its leaching sulfuric acid timeonline solutions and the analytical determination of the content of noble metal in the obtained solution, and abrignani lead once in the microwave field of the microwave range at a temperature of 550-600C without access of air, followed by repeated leaching of the product of firing successive volumes of sulfuric acid timeonline solutions in the obtained solutions analytically determine the content of gold and/or silver, summarize the obtained values, mathematically calculating the content of gold and/or silver in the original sample.

As sulfate timesaving solutions using 3% solution of thiourea and 3% solution of sulfuric acid, is widely known for leaching gold and silver ores (see, for example, Ladadika V.V., Panchenko A.F., Khmelnytsky OD Thiocarbamide leaching gold and silver ores // Hydrometallurgy of gold. M.: Nauka, 1980. p.26-35). Leaching are preferably within 1 hour at a ratio of t:W=1:2,5.

Using the proposed method allows to solve the problem, first of all, due to the fact that in the present method the original sample of the investigated material can be increased up to 500 grams, i.e. the representation of the traditional sample (25-50 g) increases by 10-20 times. Standard deviation from the microheterogeneity of the investigated materials is reduced in proportion to the square root of the mass of the sample, i.e. the increase in sample mass reduces the detection error that is associated with the microinhomogeneity of the material. Increase the representativeness of the sample significantly increases the reliability of the determination of gold and silver in ores low in their content or in the presence of the AI coarse grains of gold or silver. When using previously known methods of determination of gold and silver in sulfide ores is not possible to conduct research on the hinge of a large mass.

In addition, using the proposed method provides an opportunity to reduce the random component of measurement error due to repeated measurements of the concentration in the solution obtained after leaching. Measuring the concentration of the investigated component can be held in the several Parallels in various ways known to those goals.

The mechanism of extraction of gold and silver by the claimed method is that the roasting of sulfide ores and products of their processing in the microwave field without access of air at a temperature up to 550-600C provides a flow pertinacious firing and thermolysis process, resulting in sulfur removal with the formation of pyrite pyrrhotite (Fe7S8), which has a porous structure due process expulsion (removal) of sulfur, the latter evaporates and condenses out of the reaction zone. Multiple stepwise sequential leaching sulfuric acid timeonline solutions product of the high temperature firing provides complete recovery of the original sample of noble metals, which become available for leaching only what about after high temperature processing.

The essence of the proposed method is illustrated by examples of specific performance.

Example 1. As source material for analysis using the standard sample, namely GSO 1788-80 containing CAu=33 g/t, CAg=6.2 g/t and has the following mineral composition: quartz - 9,4%, mica, feldspars, clay minerals or 14.8%; carbonates of 4.1%; pyrite - 41,5%, arsenopyrite - 26,6%; chalcopyrite - 0,2%; sphalerite is 0.2%. Taken the sample of the analyzed material weighing 50 g, which was examined on the content of gold and silver by the claimed method. The sample was subjected to high-temperature firing without air in the microwave field of the microwave range, with output power of 0.5 kW for 4 hours, the temperature of the material in the treatment area was approximately 550C. as microwave ovens used household microwave brand Elenberg MS-1700M. To ensure the regime of firing without access of air was used sealed quartz vessel. The material obtained after microwave treatment, was subjected to consecutive four sequential leaching in sulfuric tiomochevina solution for 1 hour at a ratio of T:W 1:2,5 respectively. The slurry resulting from each leaching, filtering, separating the solution for analysis.

Determination of gold and silver in solutions for the analysis of the implementation of the conduct on the mass spectrometer ELAN 9000. The results of the mass spectrometric measurements were tabulated and counted on the content of silver and gold in the source material.

The content of gold and silver, as defined by the claimed method, amounted to: CAu=33,2 g/t, CAg=6.8 g/so

Example 2. Research used the flotation tailings dump fields in Karabash, representing the products of processing of sulfide ores. Were selected for the study hitch weight of 500, a portion of the samples were annealed without air for 4 hours in the microwave field of the microwave range when the output power 0,55 kW, the temperature of the material in the treatment zone to 600C. as microwave ovens used household microwave brand Elenberg MS-1700M. To ensure the regime of firing without access of air was used sealed quartz vessel. The sample after microwave annealing was subjected to leaching, which was carried out in 3% sulfuric acid tiomochevina solution for 1 hour at a ratio of T:W 1:2,5, respectively.

The slurry resulting from leaching, filtering, separating the solution for analysis. The resulting solid phase was subjected to repeated leaching. The sample after microwave annealing was subjected to leaching sequentially in 4 stages. Analytical determination of gold and silver in solutions for the analysis of the implementation of the conduct on the mass spectrometer ELAN 9000. The results of the mass spectrometric measurements were tabulated and counted on the content of silver and gold in the source material.

In the result, it was obtained the following result CAu=0.1 g/t, CAg=0,67 g/T. the Results of determination of components in solutions for analysis, allocated to each stage of leaching, are presented in Table 1. The data in table 1 is presented in the form of conversion of gold extracted in the solution to the initial concentration in the ore to the sum of the previous stages of leaching.

The process of burning without air in the microwave field microwave range below 550C can improve the accuracy of the determination of noble metals, because it does not allow to adequately disclose the access to the private gold (not achieved the completeness of the translation, in pyrrhotite).

The process of burning without air in the microwave field microwave range above 600C leads to the melting of the material, thereby closing the access leaching agent to gold or silver.

As can be seen from the presented examples, the use of the proposed method can improve the accuracy assessment of the contents of noble metals in sulfide materials, can be the basis for an adequate assessment of the stock and tools of scientific research in the field of "hard gold".

Table 1
Microwave roasting of the original sample without access of air, followed four sequential leaching
Analyzed theThe content in solutions for analysis at each stage of leaching, g/t
1234
Au0,0520,0830,094is 0.102
Ag0,530,627to 0.6620,67

1. The method of determination of gold and silver in sulfide ores and products of their processing, including the firing of the original sample, the subsequent selective leaching and analytical determination of the content of noble metal in the resulting solution, characterized in that the firing sample lead once in the microwave field of the microwave range at a temperature of 550-600C without air, and the subsequent leaching of the product of firing stage are sequentially input volume series is cislago timesaving solution, in the obtained solutions analytically determine the content of the noble metal and summarize the values obtained for the calculation of the content of noble metal in the original sample.

2. The method according to claim 1, characterized in that the number of stages of the sequential leaching is at least four.



 

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