Leach Residue Research Articles

Electric field-assisted leaching of valuable metals from spent lithium-ion batteries in a mixture of acetic acid and ascorbic acid

Recovery of valuable metals from spent lithium-ion batteries (LIBs) has great economic and environmental value. In this study, mixtures of acetic acid and ascorbic acid were used to leach valuable metals from the cathode plates of spent LIBs with assistance from an electric field. Thermodynamic analysis showed that the metal oxides of spent LIBs could be dissolved in the form of metal ions by adjusting potential and pH. Leaching conditions, including the concentrations of acetic acid and ascorbic acid, working voltage, reaction temperature, and reaction time, were systematically investigated. Under conditions with acetic acid concentration of 1 mol/L, ascorbic acid concentration of 0.1 mol/L, working voltage of 4 V, reaction temperature 25 °C and reaction time 70 min, the leaching efficiency of Ni, Co, Mn, and Li reached 99.8%, 99.8%, 99.8%, and 99.9%, respectively. A kinetic study revealed that the surface chemical reaction was the rate-controlling step in the leaching process. The infrared spectra indicated that polyhydroxy groups were transformed into carboxyl or aldehyde groups during mixed acid leaching. The complexity of ascorbic acid and low-valent metal ions increased with leaching time in the ultraviolet spectrum. Finally, the leach residue was analysed using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), which indicated that the metal oxides in the cathode plate were efficiently leached.

Nitrogen Removal Performance and Microbial Community Analysis of Anoxic and Oxic Process in Electrolytic Manganese Residue Leachate

Nitrogen Removal Performance and Microbial Community Analysis of Anoxic and Oxic Process in Electrolytic Manganese Residue Leachate

Enrichment of Platinum Group Metals from Spent Automotive Catalyst Leaching Residue by a Combined Smelting and Wet Extraction Method

Enrichment of Platinum Group Metals from Spent Automotive Catalyst Leaching Residue by a Combined Smelting and Wet Extraction Method

Recovery of nickel oxide nanorods from a laterite-originated intermediate product by ammonia leach-deammoniation method

Extraction of nickel from laterites, especially low-grade limonitic ores has been facing challenges related to the lack of an effective beneficiation method. A chemo-physical laterite ore processing comprising oxalic acid leaching followed by size separation of the leach residue was recently introduced by the authors as a novel method to collect small amounts of nickel values dispersed in the ore matrix into distinct oxalate particles to form an intermediate product. In the present work, the ammonia leaching of such intermediate product containing about 12 wt% NiC2O4·2H2O was accomplished. Factors such as initial ammonia concentration (NH3: 2.5–25 wt%), temperature (T: 20–50 °C), pulp density (S/L: 50–200 g/L), and sonication were examined in a series of agitated leaching tests. It was found that under the conditions of 25% NH3, T = 50 °C, S/L = 200 g/L, and 15 min of sonication, about 93% of nickel is dissolved resulting in a pregnant leach solution (PLS) with a nickel content of 7.4 g/L. Besides, the activation energy for dissolution of nickel oxalate in ammonia solution was found to be about 71 kJ mol–1 from a kinetic analysis of leaching data. The PLS was subsequently deammoniated by either boiling or vacuum-assisted gentle heating to reclaim the nickel as an oxalate salt. Electron microscopic analysis of nickel oxalate precipitates formed from ammonia solutions exhibited rod-like morphology with high aspect ratio. Deammoniation under boiling led to well-shaped and distinct particles (∼150 nm width), while the precipitates obtained under partial vacuum were splintered and finer (∼40 nm width). The pyrolysis at 400 °C in an air atmosphere of the nickel oxalate particles from the boiling and the vacuum-assisted deammoniation methods generated mesoporous NiO nanorods with average widths of about 100 and 30 nm, and specific surface areas of about 45 and 70 m2 g−1, respectively.

A novel combined metallurgy-beneficiation method for the facile and low-cost comprehensive resource utilization of low-grade kaolin solid wastes

Low-grade kaolin is the largest emissions of industrial solid waste that is difficult to dispose of and pollutes the environment seriously. From the perspective of harmless and complete resource utilization, we proposed a novel strategy that combines the wet leaching under mild conditions and physical beneficiation for the facile and low-cost high-valued utilization of low-grade kaolin that involves high-efficiency recovery of aluminum (Al), silicon (Si), and titanium (Ti). The key to successful implementation of this method lies in the new discovery that the residual SiO2 after Al extraction of kaolinite by acid leaching under specific conditions could be rapidly dissolved in dilute NaOH solution at room temperature 25 °C. This highly reactive SiO2 challenges the conventional notions of various silica species are usually chemically stable. By adjusting the key technical parameters of the thermal activation-acid leaching process, the selective and efficient extraction of Al2O3 from low-grade kaolin was realized. The acid leaching residue was then subjected to selective recovery of SiO2 by alkaline leaching at 25 °C to obtain high-quality sodium silicate. Finally, the alkali leaching residue as titanium coarse concentrate was separated by centrifugal concentrator to obtain artificial rutile (TiO2 >91.06%). The key mechanism for the formation of the highly reactive silica was also systematically studied and confirmed.

Pressure leaching of aluminum from kaolin by HCl: Experimental and DFT study

Kaolin is an important industrial mineral which has many industrial applications. It is also considered as an important source of aluminum; however, great technical challenges are required to be overcome to extract Al from kaolin. In this work, the extraction of aluminum from kaolin using HCl, as a leaching agent, was studied. Kaolin samples were collected from Wadi Al-Hafira, south of Jordan; these were crushed and ground to a particle size of 100% <75 μm. The ground samples were characterized in terms of chemical and mineral composition using X-ray fluorescence (XRF) and X-ray diffraction analysis (XRD) techniques. Kaolin was found to contain kaolinite, muscovite, and quartz as main mineral phases, in addition to anatase and hematite as trace mineral phases, while the chemical analysis revealed that kaolin contains about 36.1% Al2O3, 54% SiO2, 2.5% CaO, 1.96% Fe2O3 and 1.2% TiO2 as major oxides. The minor oxides were K2O, Na2O, and SO3. A microwave digestion vessel was used to provide a suitable environment for high pressure and temperature leaching. The effect of several leaching parameters was studied in this work including, leaching time (30 to 120 min), leaching temperature (80 to 200 °C), and molarity of leaching reagent (1, 2, 3 and 4 M). Additionally, two sources of HCl were used, including analytical grade HCl and HCl collected from the potassium sulphate industry. The extraction of four main elements were monitored during the leaching process employing ICP-OES multi element analysis technique, namely, aluminum, iron, titanium and silicon. The findings of this work suggest that the recovery of these elements increases with the increase of temperature and leaching time. The recovery of silicon decreased with the increase of acid molarity. Complete extraction of Al from kaolinite was obtained at temperatures above 180 °C and leaching time of 120 min, while Al present in muscovite was not amenable to leaching. However, traces of H2SO4 and chloride salts in waste HCl, from potassium sulphate industry, provided complete destruction of muscovite as evident from the XRD analysis of leach residues. Lower energy requirements (computed by DFT simulation) for chlorination of Al sites in reference to Si sites explains a higher recovery percentage of the former.

Precipitation of Rare Earth Element from Indonesian Coal Fly Ash Using Sodium Sulfate

The rare earth element is a critical element in many industrial sectors. Due to unbalanced supply and demand, it is necessary to look for an alternative source. Coal ash is a waste product of power plant combustion. Previous research revealed that coal ash contained levels of rare earth elements. This research uses coal fly ash from the Paiton power plant. The objectives of this study were to determine the effect of the Na2SO4 concentration, stirring rate, and temperature on the recovery of REE concentrate. The experiment was conducted in four steps: (1) alkaline leaching, the process was carried out for 2 hours at 90°C with fly ash solid to 8 M NaOH solution ratio of 1:4 to break the aluminosilicate bonds. (2) Acid leaching of residue for 4 hours at 90°C in 3 M HCl. (3) Precipitation of residue to remove the impurities such as Fe using 1 M NaOH at pH 5. (4) Precipitation of filtrate from process (3) using Na2SO4 to produce REE concentrate precipitates. The best condition to obtain the highest REE residue is conducting recovery at the concentration of 20% Na2SO4, stirring rate of 500 rpm, and temperature of 50°C, with a yield of 88.72%.

Enhanced recovery of germanium(IV) from zinc residue leachate by tartaric acid functionalized chitosan: Experiments and DFT calculation

The recovery of germanium (Ge) from zinc residue leachate has attracted increasing attention. Herein, this study report on the development of a tartaric acid functionalized chitosan (TA-CS) material serving as an efficient adsorbent for Ge(IV). The introduction of TA resulted in abundant protonatable hydroxyl and carboxyl groups, which endows materials with excellent buffering capacity under acidic conditions. Adsorption kinetics and isotherms showed a fast and efficient adsorption capacity of 57.28 mg/g for Ge(IV). In binary systems, Ge(IV) was preferentially adsorbed over Zn(II), a major coexisting ion, with a separation factor of 3.22. The SEM–EDS FT-IR, XPS and DFT results revealed that mechanisms in combination, including electrostatic adsorption, complexation, hydrogen bonding, and ion exchange, promoted the immobilization of Ge(IV) on TA. The TA-CS material also exhibited great reusability with an adsorption efficiency of 70% after 3 recycles. For the recovery of Ge(IV) in practical zinc residue leachate, the TA-CS material showed superior affinity toward Ge(IV) and a 10-fold higher of adsorption capacity compared to that of pristine chitosan. Together, TA-CS demonstrates that it is a viable and economical material for the separation and preconcentration of Ge(IV) from zinc residue leachate.

Subacute Toxicity of Wood Ash (Toka) on Behaviour, Haematological and Biochemical Parameters of Wistar rat

Toka is mostly produced from maize cob by the process of leaching, diluting decanting and removal of water residue. It is a commonly used food additive in northern Nigeria. Thirty-three Wistar rats were used to determine the acute and sub-acute toxicity of toka. The median lethal dose or LD50 of toka using the up and down procedure was discovered to be above 2000 mg/kg since administering 175 mg/kg, 500 mg/kg and 1000 mg/kg did not trigger death. However, during the 28-d study for sub-chronic toxicity study of Toka on the four test groups with graded doses of 0 mg/kg, 250 mg/kg, 500 mg/kg and 1000 g/kg. Physical behaviour such as redness of the eye started on the seventh day of the experiment while blisters on the mouth were observed from the fourteenth day of the experiment. There was no significant difference between the parameters and test groups. The findings of the current investigation revealed that there is not 54any significant difference in all the haematological parameters except haemoglobin. It also reveals various changes in the haematological parameters; White blood cell (RBC), packed cell volume (PCV), haemoglobin (HB), MCV, MCH, neutrophil (N) and Lymphocyte (L), did not show any significant difference with the control. Red blood cells (RBC) decreased significantly; this could be due to the increase in the breakdown of haemoglobin. There was an increase in the activity of ALT during the oral administration of Toka at different doses, this is an indication of the Liver malfunctioning. The outcome of this research indicated the toxicity of Toka on Wistar rats and therefore prolonged use of Toka as a food additive may have a toxic effect on some organs of the user.

Assessing the Efficiency of Ion Exchange Resins for the Recovery of Scandium from Sulfuric Acid Leaching Solutions

Scandium, a valuable element with restricted production sources mainly situated in China and Russia, is typically obtained as a by-product during the production of various materials. As the demand for scandium grows in the expanding aluminum and fuel cell industries, and with significant investments in rare earth mining in the USA and Australia, there is a need to explore alternative recovery sources. This research investigates the recovery of scandium from an acid pregnant leaching solution using ion exchange resins. The pregnant leaching solution was obtained after the leaching of bauxite residue with sulfuric acid. Commercial resins with different functional groups were tested for their performance in scandium extraction. In addition, the co-adsorption of impurities, such as iron and titanium, was studied. The feed solution consisted of 12.7 mg/L Sc and main impurities of 272 mg/L Fe and 33.6 mg/L Ti and was pretreated before the ion exchange process by acidification with sulfuric acid and iron powder addition to suppress silica gel formation and minimize the Fe(III) content in the solution accordingly. Among the tested resins, a D2EHPA-impregnated resin had high selectivity for Sc towards Ti, while a monophosphonic resin was also a promising option since it had a higher capacity for Sc but co-extracted Ti. These findings offer promising opportunities for the recovery of scandium from acid leaching solutions and could contribute to addressing the growing demand for this valuable element.

Treatment of copper-containing leaching residue by sulfation roasting followed by acid/water leaching

This research investigates the extraction of copper from copper-containing leaching residue, which includes 33.45% of copper, 14.14% of iron, 23.87% of sulfur and trace amounts of silver and other elements. Roasting the copper-containing residue under air and oxygen flow convert sulfides into sulfate, followed by water and acid leaching to extract copper. The process parameters, including leaching temperature, sulfuric acid concentration, leaching time, solid-to liquid ratio, and agitation speed, were optimized for both water and acid leaching methods. Results showed that the maximum copper dissolution efficiency was 93.12% with water leaching, and 97.16% with acid leaching. Chemical analysis revealed that the water and acid leaching residue contained 48.13% and 31.64% of iron, respectively. This study provides valuable insights into the process optimization for copper extraction from copper-containing leaching residue, which can inform the development of more efficient and sustainable methods for metal recovery.

Valorization of phosphor powder of waste fluorescent tubes with an emphasis on the recovery of terbium oxide (Tb4O7)

Waste fluorescent tubes containing yttrium, europium, lanthanum, cerium and terbium are considered important resources of rare earths. Due to the scarcity of terbium in natural deposits, phosphor powder from waste fluorescent tubes could be a potential source of terbium. The presence of terbium with stable aluminates matrix in the phosphor powder makes the terbium recovery challenging. The present paper aims to develop a process to recover high pure terbium oxide (Tb4O7) from phosphor powder of waste fluorescent tubes. In the developed process, leach residue obtained after selective leaching of yttrium and europium was treated for the recovery of terbium. The leach residue was treated by alkali roasting-water leaching to break the aluminates and phosphates matrix. Further, La, Ce, and Tb were recovered by HCl leaching. Terbium from lanthanum and cerium was separated by solvent extraction using D2EHPA as an extractant. Various parameters such as extractant concentration, phase ratio, etc. were optimized for the selective extraction of terbium in the organic phase. The counter-current process was simulated for terbium extraction. High pure terbium oxide (99.8%) was produced from the loaded organic by precipitation stripping followed by calcination. The solid residues and final products were characterized by chemical analysis, XRD and SEM-EDS.

Processing of a Zinc Leach Residue by a Non-Fossil Reductant.

The suitability of a non-fossil reductant in high-temperature treatment of a zinc leach residue was studied in laboratory-scale experiments. The pyrometallurgical experiments carried out at temperatures of 1200-1350 °C consisted of melting the residue under an oxidizing atmosphere to produce an intermediate, desulfurized slag, which was further cleaned of metals such as Zn, Pb, Cu, and Ag, using renewable biochar as a reductant. The aim was to recover valuable metals and produce a clean, stable slag for use as construction material, for example. The first experiments indicated that biochar is a viable alternative to fossil-based metallurgical coke. The capabilities of biochar as a reductant were studied in more detail after optimizing the processing temperature at 1300 °C and modifying the experimental arrangement by adding rapid quenching of the sample (to a solid state in less than 5 s) to the procedure. Modifying the slag viscosity by adding 5-10 wt % MgO was found to enhance the slag cleaning significantly. With an addition of 10 wt % MgO, the target Zn concentration in slag (Zn < 1 wt %) was reached after as little as 10 min of reduction, and the Pb concentration was also decreased relatively close to the target value (Pb < 0.03 wt %). With an addition of 0-5 wt % MgO, the target Zn and Pb levels were not reached within 10 min, but with longer treatment times of 30-60 min, 5 wt % of MgO was enough to decrease the Zn content in slag sufficiently. The lowest Pb concentration achieved with an addition of 5 wt % MgO was 0.09 wt % after a 60 min reduction time.

Assessment of combustion residual leachate volume, composition, and treatment costs

Combustion residuals and the resulting leachate from storage sites represent a large volume of wastewater in the United States (U.S.) that has not been quantified. This work estimates the constituents present, volume of wastewater, and costs of treatment for both combustion residual landfill leachate and the leachate from surface impoundment closures. Combustion residual landfill leachate produced from contact with bituminous coal combustion byproducts is generally predicted to be higher in lithium and manganese, whereas landfill leachate produced from contact with subbituminous coal combustion byproducts is generally predicted to be higher in mercury and vanadium. The annual volume of a single landfill with combustion residual leachate can reach more than 800,000 cubic meters. This leachate represents an annual volume of 26.8–42.8 million cubic meters nationally. Closing surface impoundments can yield between 830 and 1040 cubic meters of leachate nationally for a three-year closure period. Costs as low as $1.5/m3 or as high as $95/m3 are observed. Treatment trains will need to remove 72% of total suspended solids (TSS), 87% of arsenic, and 64% of mercury from landfill leachate. When applied to impoundments, these treatment trains would need to remove 97% of arsenic.

Comprehensive Utilization of Pyrite Concentrate Pyrolysis Slag by Oxygen Pressure Leaching

The preparation of high-purity sulfur and pyrrhotite by pyrolysis holds great potential to realize the high-value utilization of pyrite concentrate (FeS2), i.e., a by-product during the flotation of sulfide ore. In this study, the pyrrhotite obtained from the pyrolysis of pyrite concentrate was taken as the study object, and the effects of acid types, initial acidity, leaching time, leaching temperature, oxygen pressure, and liquid-to-solid ratio on the leaching behavior of pyrrhotite under oxygen pressure, were explored. The results show that elemental sulfur and hematite-based iron residue can be obtained by oxygen pressure leaching of pyrrhotite. It is found that the optimal experimental conditions for pyrrhotite oxygen pressure leaching are hydrochloric acid with 0.8 mol/L of initial acidity, 5 h of leaching time, 0.8 MPa of oxygen partial pressure, and 9:1 of liquid to solid ratio at 150 °C; moreover, the yield of sulfur reached 88.37%. Under optimal conditions, the leaching ratios of Fe, Pb, and Zn were 19.8%, 92.25%, and 99.11%, respectively. The sieved leaching residue was roasted at a low temperature of 500 °C, where the grade of Fe in the obtained hematite iron powder was 61.46%, and the grades of Pb, Zn, and S were 0.082%, 0.024%, and 0.1%. Clearly, the results meet well with the standard of the first grade of pyrite cinder, and this process realizes the comprehensive recovery of Fe and S resources in pyrolysis slag, which provides a superb technical route for the high-value utilization of pyrite concentrate.

Treatment of steel industry wastewater by Poly-Aluminum-Ferric-Silicate coagulant prepared from coal gasification ash

The coal gasification industry generates a large amount of coal gasification ash (CGA) which can contaminate environment by seeping harmful substances into both soil and water. In this study, CGA was used for the preparation of Poly-Aluminum-Ferric-Silicate coagulant (PAFSiC) to treat steel industry wastewater, and the effects of acid leaching, alkaline leaching, and copolymerization stages were investigated. Our results indicated that the dissolution rates of iron and aluminum from CGA were 53.49% and 55.43%, respectively, under leaching temperature at 95 °C, time at 1.4 h, and concentration of HCl at 5.1 mol/L. The dissolution rate of silicon from the residue of CGA leaching by HCl was 41.44% under leaching temperature at 75 °C, time at 0.5 h, and concentration of NaOH at 5 mol/L. The PAFSiC prepared under (Fe+Al)/Si molar ratio at 4.3 indicated the best coagulation performance, and its removal rates for turbidity, color, and chemical oxygen demand (COD) from steel industry wastewater were 93.69%, 36.47%, and 62.66%, respectively. Compared to commercial polysilicate aluminum ferric (PSAF), PAFSiC increased removal rates of for turbidity, color, and COD by 28.67%, 18.21%, and 7.38%, respectively. The coagulation efficiency of PAFSiC was influenced by pH; a removal rate of color of 54.43% was recorded from the steel industry wastewater using PAFSiC prepared at pH of 2. PAFSiC synthesized from CGA under (Fe+Al)/Si molar ratio at 4.3 exhibited a branching amorphous structure with spatial stereoscopic sense, resulting in higher capacity to bind with and remove contaminates. Our results underline the potent performance of PAFSiC as a viable solution to alleviate pollution from the steel industry.

Observations on the Leaching of Milled Black Mass with Additives

In this work, previously produced black mass was treated in sequence by milling, water leaching, and sulfuric acid leaching. Two goals were set: first, whether milling, with reductive additives, could impart reductive phase changes which would allow Li extraction to water in the water leaching; second, co-leaching of the black mass with the additive, CoS, was explored as to ascertain whether synergistic effects could be detected in a leaching system composed of reductive (CoS) and oxidative (NMC oxides) materials in the presence of redox mediator (Fe2+/Fe3+ redox pair). It was found out that in all experiments, similar Li concentration was obtained despite milling. Fluoride analysis indicated high F concentrations in the water solution and implicated formation of insoluble products such as LiF(s). Water-soluble fluoride ended up in all fractions: water leaching filtrates (ca. 500 mg/L), acid leaching filtrates (ca. 800–1700 mg/L), and leach residues (ca. 68–382 mg/kg). In acidic leaching, CoS appeared to enhance extraction of elements from cathode-active materials, improving extraction from 78 to 92% for Ni under relatively mild leaching conditions (T = 30 °C, solid conc. = 100 g/L, [H2SO4] = 1.4 M).Graphical

Technospheric mining of critical and strategic metals from nickel slag – Leaching with citric acid and hydrogen peroxide

Critical and strategic metals (CSMs), such as cobalt (Co) and nickel (Ni), are fundamental components of the high technology industry. Securing the supply of CSMs is fast becoming a priority for nations. Thus, secondary sources such as mine wastes, slags, tailings, and residues are being exploited to extract CSMs since they contain notable amounts of those metals. Recovering valuable metals from secondary sources can be categorised as technospheric mining. In this study, the extraction of cobalt and nickel from nickel slag was examined using a combination of an organic acid, citric acid, and hydrogen peroxide as the oxidant. Optimum conditions consisted of 1 M citric acid, 0.5% (v/v) hydrogen peroxide, at a temperature of 60 °C, a pulp density of 2.5%, a particle size of −100 + 75 μm, and an agitation speed of 400 rpm, for a period of 6 h. At the optimum conditions, 84.0% Ni and 91.7% Co were extracted from flash furnace (FF) slag, and 65.0% Ni and 99.1% Co from converter (CV) slag. It is expected that a combination of citric acid and hydrogen peroxide created peroxycitric acid in the solution, which is a strong oxidant and a key factor in the dissolution of the metals. The leach residue from FF slag showed a porous surface resulting from preferential dissolution within the slag structure. The residue from the converter (CV) slag mainly consisted of magnetite as a result of the dissolution of fayalite (Fe2SiO4). The kinetic studies demonstrated that the dissolution of Ni and Co from FF slag is controlled by diffusion. On the other hand, a rate controlling factor for Ni from CV slag is mixed control and for Co is a chemical reaction. Based on the temperature varied experiments, the calculated activation energy for Ni and Co from FF slag were 34.4 kJ/mol and 27.6 kJ/mol, respectively. The activation energies for the leaching of Ni and Co from the CV slag were 16.1 kJ/mol and 23.7 kJ/mol, respectively.

X-Ray Diffraction in Mineralogical Research

A brief account of role of X-ray diffraction (XRD) in mineralogical research with special reference to radioactive and atomic minerals is given. Aspects of research methodology such as sample preparation, analysis time, limitations, search match methods for identification, and complimentary techniques are also given. The most common applications of XRD in mineralogical researches related to radioactive/atomic minerals include identification of primary and secondary uranium and associated ore and gangue minerals, determination of the oxidation grade of uraninites, identification of Th, Nb, Ta, Sn, Be, Li, Zr, Hf, Ti, rare-earth elements (REE) minerals, investigations on degree of structural disordering in Nb-Ta minerals, X-ray crystallographic and substitutional solid solution studies, clay minerals, triclinicity of K-feldspar, metamict minerals and influence of the degree of metamictisation on uranium beneficiation, characterisation of leached residue, beneficiated, heat-treated products, metallurgical slags and other mineralogical studies. The results of mineralogical research are used for elucidating physicochemical conditions and geologic processes that prevailed during mineral formation

X-Ray Diffraction in Mineralogical Research

A brief account of role of X-ray diffraction (XRD) in mineralogical research with special reference to radioactive and atomic minerals is given. Aspects of research methodology such as sample preparation, analysis time, limitations, search match methods for identification, and complimentary techniques are also given. The most common applications of XRD in mineralogical researches related to radioactive/atomic minerals include identification of primary and secondary uranium and associated ore and gangue minerals, determination of the oxidation grade of uraninites, identification of Th, Nb, Ta, Sn, Be, Li, Zr, Hf, Ti, rare-earth elements (REE) minerals, investigations on degree of structural disordering in Nb-Ta minerals, X-ray crystallographic and substitutional solid solution studies, clay minerals, triclinicity of K-feldspar, metamict minerals and influence of the degree of metamictisation on uranium beneficiation, characterisation of leached residue, beneficiated, heat-treated products, metallurgical slags and other mineralogical studies. The results of mineralogical research are used for elucidating physicochemical conditions and geologic processes that prevailed during mineral formation