Home – Home – Jornals – Chemistry for Sustainable Development 2012 number 1

Comparative analysis of lithium deposits and ore manifestations of spodumene pegmatites of Siberia was carried out for the purpose of their development and substantiation of the investment attractivity for nuclear, electrochemical industry and defense technologies. The characteristics of the geological structure of ore fields of spodumene pegmatites are presented, along with the mineralogical and geochemical characterization of lithium-bearing complexes contained therein. The richest in lithium spodumene ore species are those from the deposits of the Eastern Sayan, Tuva and Eastern Transbaikalia. Comparable concentrations of lithium oxide are present in the ore from the Tashelga deposit in the Shoria Highlands. The ore from the Alakha stockwork situated in the south of the Altai Highlands has the lowest lithium oxide content; however, due to the uniformity of its distribution and substantial scale of mineralization, large-scale resources are concentrated there. After ore concentrating, the concentrate consists mainly of spodumene. Iron should be mentioned as one of the most abundant admixtures. The level of concentrate enrichment with lithium oxide is determined by its concentration in spodumene. In this respect, among the studied deposits the most promising ones appear to be the pegmatites of the Eastern Sayan (Goltsovoye deposit). We emphasize that there is a necessity to perform additional geological prospecting, chemical engineering and inspection examinations for the purpose of allocating the sites with the richest lithium ore species within the Zavitino deposit (Transbaikalia), as well as at the Goltsovoye, Belorechensk and Urik deposits (Eastern Sayan), Tastyg deposit (Tuva) and promising ore manifestations Tashelga (Mountain Shoria) and Alakha (Altai Highlands).<br>It is concluded that the spodumene pegamitites of Siberia are able to become the necessary and sufficient mineral raw material basis for the development of lithium industry in Siberia.

New data on the spreading and geochemical features of lithium-bearing underground waters in the Irkutsk Region and Western Yakutia are presented. A taxonomic partitioning of the hydrogeological section of the Siberian Platform was carried out, and promising salt-bearing zones were allocated.

Small lakes of Transbaikalia and Northeastern Mongolia united in five systems – Barguzin, Eravnoye-Gusinoozersk, Ingoda, Onon-Borzya and Eastern Mongolian – are characterized. Within the boundaries of the systems, the lakes are assorted in compact groups characterized by common chemical composition and type of geochemical evolution. Ground and surface waters feeding the lakes are characterized. On the basis of the examination of the microelement composition of lake sources (about 200 lakes) and ground waters (more than 100 sources, wells and holes), the elements concentrating during evaporation of lake waters were distinguished. The outlooks of the use of small lakes as a kind of liquid ore for the industrial extraction of some metals (Li, U, REE etc.) are considered.

Data obtained in the investigation of the microcomponential (Li, U etc.) and macrocomponential (Na, Ca, K, Mg, Cl, SO₄, CO₃, HCO₃) composition of water in salt lakes of Western Mongolia are generalized. It is revealed that the majority of salt lakes in this region are characterized by an increased concentration of a number of micro components (lithium, uranium etc.). It is demonstrated that lithium is concentrated in chloride lakes, whereas uranium does in sodium ones. Calculations of equilibria in lake water with the basic minerals of water-enclosing rocks are presented.

Economic efficiency was investigated for the integrated use of lithium-bearing raw material. The versions of industrial arrangement are considered for two kinds of raw material such as hydromineral and mining one, differing in logistics and completeness. It is demonstrated that the use of hydromineral raw material allows substantially decreasing the risks connected with the reduction in demand for auxiliary products; as well as allows one enhancing the competitiveness of production at the expense of cost saving for separate products in the course of the integrated extraction of useful components of brines in a united industrial cycle.

Isotopic exchange between the aqueous solution of lithium chloride containing ⁶Li isotope and the chloride form of double aluminium and lithium hydroxide synthesized from different aluminium hydroxide species was studied. It was demonstrated that the dependence of the level of isotopic exchange F(t) on time at the initial regions (the exchange level being less than 40 %) for the samples of double hydroxide obtained from crystalline gibbsite can be described by a diffusion equation: F(t) = (4/r₀π^1/2)D^1/2t^1/2. The diffusion coefficients of lithium are comparable with the coefficients of self-diffusion of singly charged alkaline ions in skeletal aluminosilicate such as mordenite. The exchange level for the samples of double hydroxide obtained from mechanically activated aluminium hydroxide under comparable experimental conditions is an order of magnitude greater than the exchange level for the samples synthesized from gibbsite. This is likely to be connected with a higher dispersion level of double hydroxide synthesized from mechanically activated aluminium hydroxide.

An influence of the conditions of the mechanical activation of aluminium hydroxide and lithium carbonate mixture in the planetary type activator APF and of the conditions of subsequent thermal treatment upon the phase composition, morphology and dispersity level of lithium gamma-monoaluminate (γ-LiAlO₂) is considered. Potentialities are demonstrated concerning the use of the γ-LiAlO₂ synthesized for obtaining the matrix electrolyte for a fuel element with molten carbonate electrolyte as well as within a separator for thermal lithium batteries.

A brief overview of works aimed at the investigation of the processes of synthesis of nanosized LiFePO₄ from different precursors using mechanical activation is presented; its structural and electrochemical properties are evaluated. The effect of nanosize on cycling processes including its mechanism is demonstrated. Examples of the influence of carbon component on the morphology of particles and the effect of substitution processes on the cathode properties of LiFePO₄ are described, as well as the data on the thermal stability of LiFePO4 against heating in the air. The proposed method was accepted as the basis for the industrial technology of obtaining LiFePO₄ at the JSC “Novosibirsk Chemical Concentrates Plant”.

A review of works aimed at the development of solid electrochemical devices based on lithium systems is presented. The criteria for the choice of solid electrolyte are described, a brief review of the properties of known solid electrolytes under in solid lithium batteries and rechargeable batteries are described. Special attention is paid to the properties of composite solid electrolytes. Examples of known solid primary and secondary lithium current sources differing in design and type of solid electrolyte are presented. It is shown that the composite solid electrolytes (ceramic, polymer ceramic and glass ceramic) are most suitable for use in solid lithium rechargeable batteries. A brief review of the works aimed at the development of solid supercapacitors is given. The data on solid supercapacitors with solid electrolyte based on lithium perchlorate and carbon electrode materials are presented.

Methods of obtaining carbon sorbents modified with the compounds of antimony (V) were developed for the extraction of sodium and calcium admixtures from the solution of lithium chloride. The sorption capacity of the obtained modified carbon materials under static and dynamic conditions was estimated. It was shown that the most efficient sorbent NUMS-K-1 was obtained by the saturation with SbCl₅ followed by its hydrolysis. With antimony content in the carbon sorbent up to 8 %, total dynamic capacity with respect to sodium is 2.2, with respect to calcium 4 mg/g. In the course of dynamic experiments, it was established that the residual concentration of sodium at the outlet of the sorption column reaches 0.25, calcium 2 mg/L. The obtained results meet the requirements to the purity of lithium products. The promising character of the use of carbon sorbents modified with antimony (V) compounds in the processes of lithium chloride purification from sodium and calcium admixtures was demonstrated.

The composition of kiln gas from the synthesis of lithium iron phosphate (LiFePO₄) is considered. The catalytic oxidation of the mixture of ammonia vapour and carbon monoxide is studied. The apparatus and technological scheme of purification of kiln gas of the synthesis of lithium iron phosphate is proposed.

Data on mercury concentration in various environmental components of Siberia are presented: for bottom sediments of continental lakes and in the soil of their water-collecting areas, in plants (moss, lichens, medicinal herbs, berries, mushrooms, needles) and in the litter of conifers. An increase in mercury content in the upper horizons of averaged sections of bottom sediments starting from the depth of about 15 cm was detected, which corresponds to the years 1960–1970. The dependence of mercury content on the degree of water mineralization and its mineral composition was not revealed. It was established that the concentrations of mercury in bottom sediments are determined by its concentration in the soil of water-collecting areas. The obtained results generally provide evidence of the favourable ecological status of the studied territories, while pollution with mercury has a local character. Coniferous litter, lichens and mushrooms can be used as indicators of pollution with mercury.

Demercurization of solid mercury-containing wastes with the help of oxidizing agents and mercury-removing solution of calcium polysulphide were studied. The major regularities of mercury removal from luminophore (luminescent and compact lamps), granosan and soil were studied. It was shown that this method of mercury removal allows obtaining low-toxic wastes of the 4th class of danger.