For a long period of time the level of nickel production has been determining the indicators of technical progress in many important branches of technology both in the USSR and abroad. This is the reason for the intensive development of the world nickel industry, observed at the present moment and expected in the near future.

В работах по автоклавному окислению сульфидов никеля в основном рассматривается поведение плавленного сульфида никеля, близкого по составу к хизлевудиту Ni₃S₂. Лишь в немногих освещена кинетика растворения моносульфида ни­келя NiS, одного из основных компонентов различных промежуточных продуктов никелевого производства: анодных шламов, никелевого сульфидного концентрата, полученного осаждением сероводородом, промежуточной фазы автоклав­ного растворения никелевого концентрата флотации медно-ни­келевых файнштейнов ...

In order to ensure trouble-free operation of some devices, it became necessary to study the conditions of good wetting of iron-nickel alloy products with mercury. As it is known, mercury wettability of a solid body surface in the absence of friction between the surfaces is a function of the difference of free surface energies at the solid-metal-mercury boundary. Wettability depends on the composition of the solid and liquid phases and the condition of their surfaces. When mercury comes in contact with a clean metal surface, the surface energy of the system decreases because instead of two interfaces there is one. If there is any film on the metal, preventing the contact of mercury with the metal surface, for successful wetting, it is necessary either to eliminate in advance this film, or to create conditions that ensure its rupture at the moment of contact of mercury with the metal surface.

In sulfide copper-nickel ores, as is known, there are always noble metals-silver, gold, and platinoids. Platinoids are of special importance - their value in some cases may be equal to copper and nickel. This makes it necessary to include special operations related to the extraction of noble metals in the processing of copper and nickel ores. Practice has shown that noble metals in the pyrometallurgical process follow the metal-containing product, i.e. in the course of copper-nickel ore processing they are sequentially concentrated in matte and high-grade matte. It is believed that the separation smelting process also separates noble metals into two groups: 1) gold and silver mainly follow copper; 2) platinoids follow nickel. Thus, already at the first stage of pyrometallurgical processing - in ore smelting - noble metals are selectively concentrated in the sulfide phase (matte) preferably before the silicate phase (slag). The nature of this phenomenon has not been accurately established until now. In the present work an attempt is made to reveal the reason for the concentration of noble metals in sulfides during ore smelting of copper-nickel ores and in the subsequent stages of pyrometallurgical processing - during conversion of copper-nickel matte and separation smelting.

As the gold mining industry develops, the processing of primary ores, among which sulfide ores are becoming more and more important, is increasing every year. On the other hand, in the beneficiation of non-ferrous metal ores, some gold is lost in sulfide flotation tailings and to recover it, in some cases these tailings must be subjected to additional hydrometallurgical treatment by cyanidation. The practice of modern gold recovery plants shows that in many cases sulphide ores and concentrates are resistant to hydrometallurgical treatment. Attempts to extract such gold from sulphide concentrate by conventional hydrometallurgical routes are often very inefficient. Despite the use of intensive repeated treatment, the residual gold content in tailings is very high and in some cases reaches 20-25 g/t. All this requires a more in-depth analysis of the reasons for the persistence of gold associated with sulfides. The proposed work aims to summarize and analyze the results of the study of some sulfide (pyrite and pyrrhotite) ores. Most of the experimental studies used in this paper were obtained during technological tests of the treatment of gold-bearing pyrite and pyrrhotite ores in the metallurgical laboratory of the Mining Institute in 1950- 1953.

The issue of reducing gold losses in tailings during the enrichment of non-ferrous metal ores is currently receiving special attention. The presence in most non-ferrous metal ores of significant quantities of pyrite, which goes simultaneously with gold into the tailings, gave reason to explain the loss of gold in the tailings by its close association with pyrite. It is necessary to establish whether gold is really closely associated with pyrite and is in such a finely disseminated state that it is not released during the most intensive grinding and remains inaccessible to solvents in subsequent hydrometallurgical processing operations. Experiments in the synthesis of gold sulfide and gold-containing iron sulfides have shown that pyrite and pyrrhotite formed at temperatures of 400 ° C are capable of including measurable amounts of finely dispersed gold, undetectable under a microscope even at the highest magnifications. Submicroscopic gold in some cases can be represented by sulfide dissolved in iron sulfides. Such finely dispersed gold in some cases may be a product of the decomposition of primary gold sulfide dissolved in iron sulfide. The form of gold released from pyrite in our experiments corresponds to the forms of natural gold in pyrites of some deposits.

The form of occurrence of the extracted metal is of great importance for the choice of the technological scheme of ore processing. It is important for the technologist to know in what form of mineral formations the metal is found, what is the chemical and physical connection between it and the mineral components of the ore. Direct mineralogical and mineragraphic analysis often proves powerless to solve this problem, especially in cases where the content of the extracted metals is expressed in several grams per ton of processed ore and when the form of occurrence of the elements is unusual. This situation was especially clearly revealed in the study of the form of occurrence of platinum metals in copper-nickel ores. For our ores, this problem was first solved by the Nickel Group of the Leningrad Mining Institute as a result of broadly set studies using methods of chemical and mineragraphic analysis of ore samples and maximally unified and enriched fractions with the studied components, obtained by precision methods of gravitational, electromagnetic and flotation enrichment. Only in this way was it possible to establish the composition, mutual connection of platinum and nickel and copper minerals and to make a correct forecast of the behavior of these minerals during enrichment. For the first time, such platinum minerals as cooperite, braggite, stibio-palladinite and sperrylite were diagnosed in our ores, their chemical characteristics were given and the extremely important fact of fine dispersion of the greater part of palladium in nickel and iron sulfides was established. The results of these works were summarized in a special monograph and laid the foundation for the scheme of technological processes of our copper-nickel industry.