Dust control in summer and winter periods is a topical problem associated with conducting open pit mining operations; however, at negative temperatures the additional requirements are imposed on dust suppressants. Preventive compositions are proposed, in which light and heavy gas oils, obtained from catalytic cracking and delayed coking, are used as base components. Involvement of heavy fractions allows to increase the flash point, thereby reducing the flammability of dust suppressant, improve its adhesion properties by increasing the content of polyaromatic hydrocarbons and reduce the cost of the final product. In order to improve low-temperature and adsorption properties of developed dust suppressants, heavy oil residues (cracking residue and tar) are included in their composition in various concentrations: 2-10 wt.%. Alternative compositions of dust suppressants, obtained by water emulsification of vinylated alkyd oligomer, are developed; the ability of this dispersion to form strong films on dusty surfaces is examined. The efficiency of using aqueous solution of vinylated alkyd oligomer as a summer dust suppressant is demonstrated. The results of this study include the development of new preventive compositions with improved low-temperature properties and confirmation of the theoretical part of the study by the results of performance tests on a laboratory facility.Alternative compositions of dust suppressors have been developed, which were obtained by emulsifying a vinyl alkyd oligomer (VAO) in water; the ability of this dispersion to form strong films on dusty surfaces has been studied. The efficiency of using an aqueous solution of vinyl alkyd oligomer in the summer period as a dust suppressant is shown. The results of this study are the development of new prophylactic formulations with improved low-temperature properties and confirmation of the theoretical part of the study by the results of tests of operational characteristics in a laboratory facility.
Growing productivity of mining and processing enterprises entails an increase in the volumes of liquid tailings impoundments and upstream impoundments of ore processing waste. Enterprises face the challenge of minimizing the environmental impact of waste and guaranteeing the sanitary and epidemiological safety of population. The article presents a possibility of recycling one type of such waste (clay-containing concentration tailings of apatite-nepheline and sylvinite ores, coal beneficiation tailings) by using them after preliminary thermochemical treatment as pozzolanic additives to cements and concretes, including concrete mixtures used for soil stabilization, development of territories, reclamation of mine workings, as a component of the insulating layer of landfills for the disposal of municipal solid waste. An analysis of the phase changes of kaolinite, one of the main minerals that make up clay-containing waste, in the temperature range of 200-1,000 °С showed that a change in its mineral form during heat treatment is the main factor in changing its pozzolanic activity. The effect of heat treatment of clay minerals at temperature of 700-800 °C on their pozzolanic activity, estimated by the ability to absorb calcium hydroxide (0.7 g Ca(OH)2 per 1 g of modified kaolinite), is considered. It is shown that the addition of heat-treated samples (20 % by weight) improves the quality of cement increasing its activity by 15 %, in comparison with the use of unmodified clay minerals. It was proved experimentally that partial replacement of Portland cement with thermally modified kaolinite increases the strength of consolidating stowing mixture by up to 15 %. This approach to processing of ores containing layered silicates, which provides for thermochemical modification of run-of-mine ore, intensifies the processes of tailings thickening and filtering.
This study is aimed the developing the special petroleum products, namely, preventive lubricants (PL) used in the field of solid minerals transportation. The surface and adhesion characteristics of the prophylactic compositions developed earlier on the basis of thermodestructive and thermocatalytic processes products of oil refining are investigated. It is set that the prophylactic agents contain the far of surface active substances, such as resins, pyrobitumens and other polyaromatic hydrocarbon compounds: in the heavy gas-oil of the catalytic cracking their content is above 45.96 %, in an easy gas-oil – 15.07 %, that results in the improvement of viscosity-temperature properties of products and promotes their oiling ability. The basic amount of compounds with high superficial activity is contained in heavy fractions of oil, and in the process of processing concentrated in a petroleum residue - petroleum tar that was used as depression addition in mixtures of prophylactic agents. For protecting of metallic surfaces of mountain transport from a direct contact with the transported material in the conditions of the lowered temperatures it is recommended to apply composition of the catalytic cracking mixtures with content of petroleum tar from 2 to 5%. <span style="opacity: 0;"> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </span>
In this research, a new method for evaluating the lubricating properties of prophylactic agents was developed. For the method, specialized metal models and a press with a strain-gauge s-shaped gauge, using for recording shear load indicators, were designed. Using the new method, prophylactic agents based on mixtures of light and heavy gas-oil catalytic cracking and delayed coking with the addition of tar or cracking residue as depressor additives were analyzed. A research of the hydrocarbon composition of the prophylactic agent, which was correlated with the removed shear load diagrams, was also made. As a result, the dependencies of the lubricating properties of fuels with a change in their fractional composition were identified, and the most effective PAs were determined.
This study is aimed at developing the special petroleum products, namely, preventive lubricants (PL) used in the field of solid minerals transportation. The surface and adhesion properties characteristics of the prophylactic compositions developed earlier on the basis of thermodestructive and thermocatalytic processes products of oil refining are investigated. It has been found that preventive lubricants contain a significant amount of surfactants, such as resins, asphaltenes and other polyaromatic hydrocarbon compounds. The main quantity of compounds with high surface activity is contained in high-boiling oil fractions, and during its processing it is concentrated in the oil residue - tar, which was used as a depressant thickening additive in mixtures of preventive lubricants. The dependence between the content of tar in the composition of lubricants and their adhesion ability, surface tension, wetting and lubricating properties is revealed. Surface properties of preventive lubricants were assessed by parameters such as surface tension and wetting contact angle. Studies have confirmed that the introduction of tar as a depressant additive improves the low-temperature characteristics of lubricants, as well as its small concentrations cause a decrease in the value of surface tension and the contact angle of wetting, which improves the surface and adhesion and wetting properties of the PL. To protect the metal surfaces of mining transport from direct contact with a wet finely dispersed transported material, it is recommended to use a composition of catalytic cracking process gasoil mixtures with a tar content of 2 to 5% under low temperature conditions.
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