According to the production and financial results of the world's gold mining companies in the outgoing year 2022, we can judge that the total volume of sales of the precious metal, as well as revenues, declined. Russia, of course, is no exception. For instance, the Polus Group reports that its total cash costs in the first half of 2022 rose by 12% to $435 per ounce. This was due to an increase in costs and capital expenditures in almost every business unit as well as a decrease in the average grade of gold in the ore.
Profits are also falling. Adjusted EBITDA in the reporting period fell by 26% to $1,215 million, compared to the same period last year. Of course, the profitability of the industry is still high, but there is a clear trend, so one of the most important tasks for the management of specialized companies in the near future is to reduce the cost of production of the yellow metal.
It is especially important for deposits with heterogeneous geological structure. For instance, the Kuranakh ore field in the Aldan district of the Republic of Sakha (Yakutia), which is being developed by Polyus Aldan, is characterized by uneven distribution of the useful component. Moreover, the rock mass there is composed of several types of rocks which may have different physical and mechanical characteristics. That is why during blasting operations, which always precede mining, engineers usually do not spare explosives in order to avoid formation of large oversized lumps.
However, another problem arises here. If the ore body is impacted too much, its contour can shift significantly. In this case, part of the useful component will remain in the waste rock, which will be sent to the dump. And the averaging warehouse, where the technological mixing operations, necessary for the processing plant to receive homogeneous raw material, will receive ore with a lower gold content. Considering that right now the figure is already only 1.6 grams per ton, the number of such situations certainly needs to be minimized.
"We don't have a thorough understanding of the structure of the rock mass at the place where the explosion is made, so the explosive is usually really laid down with some reserve. Deviations from optimal values, of course, lead to an increase in the cost of production. You can change the situation and distribute the energy of the charge more rationally if you get accurate information about the structure of the block being prepared for detonation," explained Ramil Zigangirov, a postgraduate student at the St. Petersburg Mining University.
As a member of a group of scientists from the university, he is working on substantiating the optimal energy consumption for drilling and blasting by the example of the Kuranakh ore field. This year, the young scientist has already travelled to Yakutia twice to obtain materials for specialized laboratory research.
"We drilled several 15-meter engineering-geological wells in different areas of the deposit that Polus Aldan is developing, from where we collected rock samples from different depths - limestone, sandstone and loam. And then in two meters from each of them they drilled technological wells (identical to the boreholes, where the charge is usually placed). In this case, the work was carried out by a machine with sensors installed on it, fixing the drilling parameters. Now in the laboratory we are comparing them with the strength characteristics of the samples from the corresponding depths, which in the future will enable us to obtain in the process of drilling clarifying information on the structure of the block prepared for detonation and adjust the volume of explosives used there," said Ramil Zigangirov.
His colleague Vyacheslav Makkoev deals with another, no less important problem - preventing the formation of excessively small fractions, the presence of which also leads to losses of useful component. It is formed both in the process of explosion and after the rock mass passes through the crushing and sorting complex. This happens because under the influence of the energy produced by the charge explosion, a large number of micro-cracks arise in individual pieces of rock mass of different sizes, which reduces their strength characteristics. In further crushing, they can literally turn into dust.
"The presence of a certain number of microcracks in the pieces depends directly on the magnitude of the stresses formed in the rock massif due to the explosion. But no one has yet found a correlation between the distance to its source and the value of the stresses generated in the rock. So, this is a very topical problem for the mining industry, a solution to which scientists at St. Petersburg Mining University are also working now. During recent industrial experiments at the limestone deposit which the company "Polus Aldan" develops for its economic needs, we conducted research on the formation of stress waves at different distances from wells, charged with various explosives. Sensors recorded displacement accelerations, which will be converted to stress values. At the moment we are processing and interpreting the results. We are working both on specialized software and on our own software, which is currently going through the registration process. Here we are 100% confident in the algorithms and modeling methods, as we developed them ourselves," emphasized Vyacheslav Makkoev.
Both young men say that the success of any scientific study depends on careful planning of experiments, as well as the ability to correctly process and interpret the results. Equally important is knowledge of the methods that scientists have used in similar studies and the results they have achieved. But the most important thing is the sincere desire to engage in real science, and from the very beginning of education at the university.
The St. Petersburg Mining University has all the conditions for this. Students here can obtain the status of "assistant scientist" from the very first year, which allows them to start working on projects that interest them under the guidance of experienced mentors. The second stage - "young researcher" - is already a full-fledged member of the research team. The next stage - "Research Engineer" - is open to fifth-year students who seriously plan to pursue a career as a scientist.
