Introduction: This article aims to discuss the physico-chemical features of the agglomeration process of phosphorus fines using phosphate-siliceous shales and oil sludge. Methods: The composition and structure of the starting materials and physico-chemical transformations under thermal influence are studied using IR spectrometry and differential thermal analysis methods. Results: The results of IR spectrometric analysis of the phosphate siliceous shales are characterized by intense peaks at 493.78, 547.78, and 678.94 cm^-1, corresponding to Ca-O-P compounds. Moreover, the wave oscillations in the region of 837.11-995.27 cm^-1 indicate the characteristics of Si-O valence bonds, and in the region of 1114.86-1431 cm^-1 depict the characteristics of Si-O-Al compounds. The IR spectrum of oil sludge is characterized by the presence of wave oscillations in the region of 1411.89-2904.80 cm^-1 corresponding to petroleum components. Conclusion: The differential thermal analysis of the investigated sample of phosphate-siliceous shale does not have intense endo- and exo-effects, and it is characterized by a significant predominance of hydrate compounds of aluminosilicate and carbonate components.

The purpose of this study is to develop a multiphysical model of agglomeration of low-grade phosphorites with the addition of phosphate-siliceous shales and oil sludge. To achieve these tasks, a numerical approach was used in the COMSOL Multiphysics environment, based on solving the related problems of heat transfer and hydrodynamics during heat treatment of the material. A laboratory vertical tubular furnace made of heat-resistant quartz glass with electric heating was used to study the effect of the temperature field and the velocity of gases on the degree of sintering and the dynamics of phosphorous agglomerate formation under various technological conditions. It has been established that the optimal temperature for the agglomeration process is a layer temperature of 950–1000 °C at a gas flow rate of 1.5–2 m/s, which ensures the formation of durable granules and minimizes sintering heterogeneity. The maximum sintering layer height of the test charge reaches 210–230 mm at pressures of 0.015–0.027 MPa. A comparison of the numerical simulation results with experimental data showed a good agreement, which confirms the practical significance of the proposed model for the design and optimization of industrial processes of agglomeration of phosphorous raw materials. Modern physical and chemical analyses have established the phase, microstructural, and element-by-element characteristics of the studied phosphate-siliceous shale and the product of agglomeration firing. The results of modeling the hydrodynamics of the charge agglomeration process can be recommended to increase the efficiency of processing phosphate-containing waste and reduce energy consumption.

Introduction: The article presents the results of chemical and physicochemical analysis of initial lithium-containing hydromineral raw materials and sorbent based on bentonite clay with titanium oxide addition. Methods: It is established that the mineral is montmorillonite group and kaolinite according to the results of the analysis of the microstructure and elemental composition of bentonitic clay of the Darbazinsky deposit. Brine is characterized by the change of lithium chloride content in the range of 403-1001 mg/l. Physical and mechanical characteristics of the obtained sorbents based on bentonite clay and titanium oxide additive are characterized by a high mechanical strength of 5.31 MPa, density of up to 2,6 g/cm³, and specific surface area of 1572 cm²/g. The technological parameters of sorption extraction of lithium chloride from lithium-containing hydromineral raw materials were optimized using the system analysis “STATISTICA” developed by StatSoft company. It is established that to increase the rate of lithium chloride extraction from brine, it is necessary to maintain the rate of brine flow within 8 l/min at maximum humidity of solution output up to 43g/m³ on the basis of the obtained volumetric graphical dependencies. Results: The microstructure of the used sorbents with titanium oxide addition up to 20% is characterized by the predominance of lithium chlorides, which are represented by heap-shaped, prismatic crystals. Conclusion: The maximum amount of lithium chloride in the form of clusters of light-white crystals of tabular shape on the surface of the sorbent is observed at increasing the content of titanium oxide up to 40%.