The accumulating capacity of tailing ponds by technology infusion of pulp preliminary clarification in the alluvium charts with its subsequent thickening and storage in the form of a highly concentrated pulp at the bottom of the pond is proposed by authors in the work. For the first time, the time dependence of filling a temporary pond on the ratio of the initial and condensed slurry concentrations for such technologies is obtained. The formula for calculating the degree of condensation is proposed. It provides the parameters selection and justification of equipment for removing water from a temporary pond as the map is filled with the accumulating capacity restoration of tailing ponds. The calculation results for the proposed dependencies allow us to establish: the necessary values of the thickening degree of the hydromixture, the possible intervals of the change in the pulp flow before and after thickening, as well as the volume of water taken from the temporary pond, depending on the concentration of the slurry entering the pond from the alluvium maps, its volumetric flow rate , geometric parameters of the technology for waste storage and the operation duration of a temporary pond.

The results of theoretical study of operation of continuous furnaces heated by natural gas, renewable hydrogen, and their mixture are presented. The furnaces have the same design, but significantly different energy efficiencies due to different heat losses and capability of recuperative fume gas heat utilization system. The measures to reduce heat losses and to increase air temperature for fuel combustion can reduce specific fuel consumption for metal heating and carbon dioxide emissions by 25.8% for natural gas furnaces. For furnaces operating on mixture of natural gas and hydrogen, a greater reduction in carbon dioxide emissions is achieved in furnaces with worse energy efficiency, but with greater fuel consumption for metal heating. The paper shows the possibility of converting a furnace with better energy efficiency indicators to be heated by mixture of natural gas (75%) and hydrogen (25%). The measure reduces the natural gas consumption and carbon dioxide emissions to 9.2% due to the use of hydrogen with specific consumption 13.81 m3 per ton of metal. To ensure the same costs for metal heating when transferring continuous furnaces from natural gas to hydrogen, or their mixture, the ratio of prices for natural gas and hydrogen should not exceed 0.301-0.312.