Characterization and Beneficiation of Ethiopian Kaolin for use in Fabrication of Ceramic Membrane

Kaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt.% SiO2, 24.9 wt.% Al2O3, 2.4 wt.% Fe2O3, and 8.22 wt.% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt. %) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120°C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4 % was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low-cost kaolin-based ceramic membrane. After firing at 1100°C the ceramic membrane was found to have a mass loss of 11.04 ± 0.05%, water absorption of 8.9 ± 0.4 %, linear shrinkage of 14.5 ± 0.05%. It was demonstrated to be chemically stable, having less than 3 % mass loss in acid solution, and less than 1 % mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.

Mechanochemical technology of iron extraction from enrichment tailings

The article describes the results of studies on ore dressing waste processing at the enterprises of the Kursk Magnetic Anomaly with production of metals and building materials. About 1.8 billion tons of tailings were stored there. Significant feature of deposits formation is division of tailings by size and specific gravity in water stream, since tailings are transported from the enrichment plant to the tailing dams by hydrotransport. Characteristics of the tailings from wet magnetic research method was applied, including system analysis and scientific generalization, data processing using methods of statistics, probability theory and mathematical modeling. The authors have systematized the results of tailings leaching of following types: agitation leaching in percolator, agitation leaching after activation in disintegrator in the dry state and reagent leaching in disintegrator. Regression analysis of experimental data have been carried out, on the basis of which graphs of dependence of iron extraction on the values of variable process factors were constructed. The used enrichment technologies are limited by extraction limit, which results in processing tailings. The use of these tailings by traditional technologies is not economically efficient, and upgrading of enrichment processes is advisable using hydrometallurgical and chemical technologies. Promising direction in metals extraction from mining waste is combination of processing technologies based on possibilities of both chemical enrichment and activation in disintegrator. It was determined that mechanochemical activation of tailings in disintegrator simultaneously with leaching can significantly increase extraction while the processing time is reduced hundredfold. Recommended technology may be in demand at mining enterprises with the prospect of transition to underground mining.

Elaboration and implementation technology of concentration of Magnitogorsk steel-works slime tailings

The problems of processing iron ore tailings of wet concentration plants and wastes with high content of iron, contaminated by oil products are actual from both points of view of ecology and economy. One of the reasons restraining solving the problem is absence of technologies ensuring to involve such wastes into industrial turnover. In the process` of the research, composition and opening degree of ore and non-metallic minerals of concentration slime tailing of Magnitogorsk steel-works (MMK) were studied and technology of their concentration was elaborated. Taking into consideration the contamination of initial slime tailings of MMK, it was proposed to accomplish their preliminary de-sliming to remove vegetable remains and clay slimes by disintegration in a screw-toothed crusher and washing in a spiral classifier. Results of wet magnetic separation (WMS) of the initial slime tailings of MMK, made at JSC “Uralmekhanobr” presented, the slimes having natural coarseness of –2.0+0.0 mm. It was established that WMS at the magnetic field intensity of 1500 Oe ensures effective removal of magnetite, aggregates magnetite-hematite-goetite into magnetic product. Iron content in the magnetite concentrate was varying from 61.5 to 62.6%. For processing of slime tailings of MMK, magnetic separation was proposed by high-gradient magnetic separator with permanent magnets, created specially for these purposes by “ERGA” company. To increase iron extraction degree, it was proposed to apply gravitation methods of concentration of nonmagnetic product, obtained at high-gradient WMS. It enabled to increase iron content in the final magnetite-hematite concentrate up to 59%. A technological diagram of oiled slimes processing presented. Tests with oiled slimes of bottom deposits of metallurgical production under pilot-industrial conditions of MMK exhibited a possibility to obtain additional iron concentrate with total iron content of 62.47% while oil content in it was less 0.3%.

Isolation and Molecular Characterization of Two Bacterial Strains with Higher Bioleaching Potentials, from Agbaja Mines (Kogi State, Nigeria)

Bacterial strains with higher bioleaching capacity (BC) are relevant for the mining industry, being more eco-friendly methods, for instance more than cyanide based extraction. Microbiological samples were collected from selected sites in Agbaja Mines, which after a growth enrichment step, cultures were screened for iron BC, including chemical quantification of iron species. Strains with the highest BC were morphologically, biochemically and molecularly characterized. Two bacterial strains with iron BC Leptospirillum sp. And Acidithiobacillus sp. (AGBAJA-1 and AGBAJA-2, respectively) were isolated from Agbaja Mines of Kogi State Nigeria. Bioleaching studies carried out shows that prior to inoculation of the iron ore solution with the organisms, raw Agbaja iron ore had a concentration of 25.10 mg/g iron while Zinc, Copper and Lead were 1.3903 mg/g, 0.094 mg/g, and 0.2813 mg/g respectively from X-ray diffraction analysis. The degree of bioleaching as a function of the amount of iron leached into solution was higher (in four weeks bioleaching test) than the other metals. Molecular characterization by sequencing the 16S ribosomal unit, amplification with universal primers, yielded high quality amplicons that were sequenced. Their phylogenetic/Blast comparison showed more than 97% relationships with Acidithiobacillus ferroxidans ATCC 23270 and Leptospirillum ferrovirans DSM 15468, families of bacteria in the National Centre for Biotechnology Information (NCBI) data bank. These are moderately thermophilic acidophilic bacteria that may represent an opportunity for developing a greener iron extraction process.

The Research of the Carbothermic Solid–Phase Red Mud Reduction Process in the Presence of Sodium Sulphate

Russia has accumulated about 600 million tons of the red mud that is alumina production waste generated by Bayer method, but currently only a small amount of the total accumulated red mud is recycled. Solid–phase carbothermic reduction of red mud in the presence of sodium salts with magnetic separation can be a promising method for iron extraction. In this paper, the effect of the addition of sodium sulphate on the reduction of iron–containing phases and the growth of iron grains during solid–phase carbothermic reduction of red mud was investigated. The results show that 10% sodium sulphate additive significantly accelerate the growth of reduced iron grains, but decrease the degree of its reduction at temperatures above 1100∘C. The explanation of mechanism of sodium sulphate effect on the iron grain growth was proposed. Optimization of sodium sulphate amount, temperature and holding time can lead the development of effective technology of iron extraction from red mud by solid–phase carbothermic reduction. Keywords: red mud, solid–phase carbothermic reduction, sodium sulphate

Til fjells med spade og graveskje. Et tilbakeblikk på de første vassdragsundersøkelsene og andre undersøkelser i sørnorske fjellstrøk

The author took part in the first comprehensive investigations along the watercourses in the South Norwegian mountain areas from 1958 and onwards. She looks back on the many previously unknown archaeological sites she has taken part in discovering and excavating: Stone Age sites from the Mesolithic and Neolithic Periods, Medieval house-sites and farm complexes, and Iron Age and Medieval iron extraction sites. Some of the results are compared to knowledge and opinions prevalent in the time before 1958, and some important improvements in fieldwork practices are briefly mentioned.

Development of Concentration Technology for Medium-Impregnated Hematite Quartzite of Kryvyirih Iron Ore Basin

Introduction. Trends in developing Ukraine’s metallurgy in the context of using its mineral raw base indicate prospects for mining hematite quartzite deposits. Problem Statement. The problem of producing high-quality hematite ore concentrates is associated with the fact that aggregates of martite, goethite, marshallit quartz, and other low hard minerals can be easily reground while crushing and grinding. This results in increased content of fine particles (slimes), which decreases selectivity of separating ore and non-metallic minerals. One of the ways to solve this problem is gentle ore grinding Purpose. Developing a technology of dry and wet concentration for hematite quartzite from Kryvyi Rih Iron Ore Basin. Materials and Methods. While conducting the research, a set of methods are used including generalization of research data; chemical and mineral analysis of ore and concentration products prior to and after concentrating by magnetite and gravitation methods; mathematical modeling of processes; technological testing in laboratory and industrial conditions. Results. Magnetic and gravitation separation is used for hematite ore concentration. Sintering ore with Fe content of 55.1% and concentrates of 62.32-64.69% Fe have been produced from hematite ore. Iron extraction in marketable products makes up 73.6-80.49%. Conclusions. There have been developed technologies for dry and wet concentration for hematite quartzites of Kryvyi Rih Iron Ore Basin. For the first time, magnetic separation has been suggested to be used for hematite ore concentration. This has enabled producing concentrates with an iron content over 64.0%, decreasing ore grinding front by at least 40% as compared with the initial one, and reducing operation and capital expenses by over 30%.