Background. According to the Spatial Development Strategy of the Russian Federation for the period up to 2025, the production of mineral heat-insulating materials, including mineral wool, has been included in the list of promising economic specializations of the constituent entities of the Russian Federation. The production of mineral wool includes two main technological stages; they are obtaining melt of the required chemical composition and fiber formation with the formation of a layer. Melting of silicate materials is often carried out in low- shaft furnaces operating on solid fuel (coke, anthracite, various grades of coal), providing the melt with the properties necessary for fiberization: fluidity, dynamic viscosity and surface tension. The relevance of the study is the development of process parameters for low-shaft smelting that enable the complete replacement of coke with long-flame coals. Also it is necessary to improve the operational capabilities of the units through two-level blast injection and preheating, the use of pulverized coal injection, and novel designs for the recuperator and proportioning feeder.
Materials and methods. Experimental melts have been carried out in a low-shaft furnace, while long-flame coals of OJSC Razrez Taldinsky (Kemerovo Region – Kuzbass) have been used as fuel. The low-shaft furnace is equipped with a radiation-convective recuperator, which provides heating of blast air up to 550 °C and a proportioning feeder to supply pulverized coal fuel. The composition and temperature of the gases have been determined using a VarioPlus Industrial gas analyzer of MRU GmbH. The temperatures of the silicate melt at the furnace discharge, and the temperature of fuel lumps in the shaft of the low-shaft furnace have been determined using C-3000.4 spectral ratio pyrometer.
Results. A series of experimental melts has been carried out at the low-shaft furnace of Closed Joint-Stock Company Isolit (Novokuznetsk) with an internal diameter of 1250 mm in order to obtain an oxide melt from dump blast-furnace slag and rock – diabase, used for the production of mineral wool products. The composition of the gas phase has been analyzed, and a technical justification is presented for the necessity of key design modifications for an industrial complex based on a low-shaft furnace with expanded technological capabilities. It has been established that when coke substitutes specifically long-flame coals are used in low-shaft furnaces, the smelting of oxide materials can be carried out at a material load level of (2,5–2,8) D. The blast preheated to 450–500°C must be injected into the oxygen zone in equal amounts at two levels (rows of tuyeres) spaced 250 mm apart. Injecting pulverized coal fuel into the blast necessitates raising the blast temperature by 10–12°C and reducing the volumetric flow rate by 1–1.2% for every percent of pulverized coal fuel introduced.
Conclusions. The study conducted made it possible to develop recommendations to regulate the melting regimes of silicate materials using long-flame coals as fuel. The feasibility of a two-level blast supply has been examined based on calculated data regarding the length of the oxygen zone, alongside an assessment of the potential for injecting pulverized materials and the parameters for blast preheating.