The aim of this paper is to define and select stable zones in the off-gas duct of an ore-thermal furnace using a mathematical model. This is needed to increase the effectiveness of exhaust gas composition control in metallurgical silicon production. Methods. The goals of this study were achieved by means of computational fluid dynamics. A model with a water-cooled furnace roof as well as a model comprising steel gas passes with a sliding shutter was developed using ANSYS Fluent software. Both models were symmetrical to ensure a uniform gas-dust distribution, which allowed us to test the adequacy of the obtained models. The models were based on the Navier–Stokes equations system as well as on a discrete phase model (DPM) that was developed using the Euler–Lagrange method. Results. As a result of the modelling, a transition flow mode (Re 0-7437) was revealed behind the sliding shutter. As such, it can be assumed that the most suitable place for measuring equipment to be installed is directly behind the closed part of the sliding shutter.

Production of metallurgical silicon for Al – Si alloys and silumins is of strategic importance and defines the future of a great number of Russian industries. Reducing the weight of commercial silica, which belongs to the expenditure side of the balance, is the key resource-saving objective of the silicon industry. In today’s environment, it is necessary to develop a monitoring and control system for quartz burden used for the production of metallurgical silicon as it would help tackle the issues caused by the reliance on different sources of raw materials, which can differ in terms of impurities content. This can affect the energy performance of the smelter and the quality of the final product. At the basis of the proposed system there lie mathematical calculations and models built with an account for the physicochemical and polymorphous transformations of the quartz material during smelting in an ore-thermal furnace. The paper relies on the relationships obtained earlier that show how the amount of microsilica and the type of emissions are determined by the chemical composition and the size distribution, the structure of quartz material and the smelting temperature. A CFD model of the exhaust duct of the furnace was used to obtain new data on dust and gas emissions. As a result, an algorithm was built that help analyze how the quality of the mineral material influences the amount and the type of emissions generated by silicon industry. The authors implemented a central data acquisition and analysis module that links the chemical composition with the size distribution of three samples of the quartz material while coordinating them with the key smelting parameters (i.e. speed, exhaust gas pressure, electric mode). The material balance monitoring and control software, which accounts for impurities as elements and compounds, as well as transition and phase states of silica at all process stages, enables to control the output of waste in the form of microsilica of required structure in order to process it and obtain high value-added materials. The proposed balance monitoring and control scheme will help raise the process efficiency by 15–20%.

One of the key problems of metallurgical production is the quality fluctuations of feedstock such as ores, concentrates and metallurgical charge. The chemical and mineralogical composition of the ore and their stability in the ore flow remain the main ones when assessing the significance of indicators characterizing the quality of the mineral in general. Analysis of production data of industrial silicon smelting in ore thermal furnaces has shown that the efficiency of the technological process, the volume of dust emissions and the purity of the final product depend on the quality of quartz raw materials. Ore quality is determined by such functional characteristics as percentage of harmful impurities, strength of ore mass, mineral and structural composition, moisture, etc. Stability of ore mass composition has the most significant influence on the results of metallurgical production. To solve the problem of accounting for fluctuations in the chemical composition of quartzite, the use of technical vision system is relevant. The paper describes an automatic system for analyzing the quality of quartz raw material for the production of metallurgical silicon based on the evaluation of visual characteristics of quartzite. The developed algorithm is based on colour filtering of images of mineral cuts. The result of the work is the data on the mass amount of iron impurity inclusions, and the average reliability of the estimation correlates with the data of X-ray spectral analysis based on the test results on average by 90%. Positive effects of implementation of the proposed vision system are the efficiency of quality assessment during unloading and preparation of raw materials, which allows taking measures to adjust the proportional composition of the charge of the ore thermal furnace.