Chromite Research Articles

Silicate mineral inclusions in chromite from the Eastern Bushveld complex: Implications for the origin and evolution of hydrous melt during chromite mineralization in the Critical Zone

Silicate mineral inclusions in chromite from the Eastern Bushveld complex: Implications for the origin and evolution of hydrous melt during chromite mineralization in the Critical Zone

Archaeology and alchemy applied: Experimental reproduction of Persian chromium crucible steel making

In a recent publication, we presented the earliest archaeological evidence for high-carbon steel alloyed with c. 1–2 percent by weight chromium, dating to the early 2nd millennium CE, and postulated that this ‘Chahak process’ was based on the addition of dried organic matter and chromite mineral as part of the charge of a closed crucible which was then fired to c. 1350 °C to produce steel. Here, for the first time, we present experimental proof that the direct reduction of chromite sand in the presence of liquid steel using common organic matter as reductant can lead to the addition of several percent by weight of chromium to the steel. In contrast, manganese oxide remains largely unreduced in the slag, despite forming a much larger part of the total crucible charge. This is in accordance with the lower reducibility of this oxide. We report the necessary operating conditions and highlight some of the constraints limiting the success of the process, and document the composition of the resulting slag and chromium-containing high-carbon steel. Our controlled crucible steel making experiments for the scientific reconstruction of the Chahak process are based on the combination of alchemical (Biruni’s crucible steel making recipe), archaeological and analytical evidence. We found the results support the alchemical recipe ingredients, and closely match the archaeological production remains, and the composition of the only currently known early Islamic chromium-rich steel artefact.

Physical and chemical studies of finely-dispersed slurry tailings of the Donskoy Ore Mining and Processing Plant (DMPP) for chemical beneficiation to produce chromium concentrate

During the processing of chromium ores, chromite concentrate is obtained for the production of ferrochrome, and waste is also collected - tailings beneficiation. Fragment and sludge tailings depending on the beneficiation technology. Finely dispersed sludge tailings of the Donskoy MPP of Kazchrome JSC are stored at the Dubersay and Akzhar tailings, which are man-made deposits (MMD) or man-made mineral formations (MMF). To develop a technology for processing sludge tailings, which contain up to 30% chromium oxide, their physical and chemical studies were carried out. According to the chemical analysis of sludge tailings, it follows that research should be directed to the removal of magnesium and silicon oxides, thereby increasing the content of chromium oxide to a standard chromium concentrate. A very thin dissemination of chromite with minerals of host rocks necessitates additional grinding of intermediate products, which are intergrowths of chromite with waste rock. According to the results of fractional analysis and IR spectroscopy, the content of a large number of flocculants in the studied sludge tailings and a large number of particles with a particle size of less than 20 μm, which, in heavy liquid solutions, due to its small size, is in suspension and does not stratify, was revealed. According to the granulometric composition, it was determined that the sludge minus 0.071 mm must also be classified into 0.04 and 0.02 mm and enriched each class separately. It has been established that in order to obtain high technological performance, the traditional gravitational beneficiation scheme used at the DMPP is technologically cumbersome, because includes operations of flocculant disintegration, classification, grinding, beneficiation on concentration tables of each size class, regrinding of intermediate products. The results of the physicochemical study of chromium sludge tailings showed the need for a combined beneficiation scheme, including chemical enrichment with finishing of chromium concentrate by gravity beneficiation.

Геохимия хромового рудогенеза

The formation of chromium ore deposits is governed by the geochemical parameters of chromium, which significantly contribute to its accumulation in the residual mantle melt, and in exogenous conditions on the formation barrier in the composition of volkonskite. Geochemistry determines the mineral composition of chromium-spinel ores and their technological properties and applications.

Collaborative resource utilization of hazardous chromium ore processing residue (COPR) and C-bearing dust during limonitic laterite sintering process

Much chromite ore processing residue (COPR), which is defined as hazardous solid waste due to virulent Cr (Ⅵ), is produced from chromium salt industry. C-bearing dust from steel industry is a kind of typically solid waste with poor surface activity. The iron ore sintering process has the potential on large-scale harmless utilization of COPR and C-bearing dust. This study proposes a new approach of co-utilizing COPR and C-bearing dust during limonitic laterite sintering process. The negative influence of COPR and C-bearing dust on permeability was offset by the fuel attribute of extra C from C-bearing dust. The results indicate that, while 6% COPR and 8% C-bearing dust were added, the tumble index and yield of the sinters were basically equal to those of the blank samples. The toxic Cr (Ⅵ) was reduced to Cr (Ⅲ) which was concentrated in high alumina spinel phases during the sintering process. The obtained sinters were identified as nontoxic, and no secondary waste was generated throughout the clean utilization process.

The Strategies of Chromite Terrace in Sukinda Valley, India: An Appraisal

Iron chrome oxide (FeCr 2O4), is a commercially viable and major ingredient of stainless steel. The Odisha state in India possesses 98% of the pre-Cambrian India’s Chromite ore deposits in Sukinda valley, Jajpur District. To meet the present escalating demand for chromium in steel industries, it is urged to extract more chrome ore to satiate domestic needs. The depletion of chrome deposits, rise in demand, fewer chrome mines, and less conversion from tailings increase of more toxic hexavalent chrome ion level in the geo-bio hydrosphere, shall aggravate health concerns for the people, fauna, and flora in Sukinda Ultramafic Complex (SUC).
 The present quest is a collection of chromite ores and tailings. A chemical study is done by using the X-ray fluorescent spectrometer. An insitu/GIS study of the Sukinda ultramafic complex by using Arc-GIS, and ERADAS software has been done to originate hydrology, aspect, and hill-shade map of the valley. The literature, and as an inhabitant of the area helped in preparing the strategic plan through Environmental Impact Assessment and Environmental Management Plan. 
 CR (III) is a dietary requirement. The anthropogenic activities and atmospheric exposure have converted Cr (III) to Cr (VI) in SUC and have surpassed the recommended values. The noxious Cr (VI) in the geo-bio-hydrosphere shall invite health and environmental concerns in the future. The aboriginals of SUC are economically burdened with food insecurity, poor livelihood, health, and of formal societal values. The Sukinda Valley ore samples contain 50% chromite ore is economic. But the >7% of CR (III) ore in the tailings and overburden shall warrant the future expected exorbitant Cr (VI) in the geo-bio-hydro environment of Sukinda valley.

FRACTURED TECTONICS OF CHROMITITES OF THE MAIN SARANOVSKOYE DEPOSIT (PERM KRAI)

The Main Saranovskoe deposit is one of the largest chrome deposits in Russia. The chrome ore bodies are localized in the ultramafites of the Northern Saranovsky massif which has been studied since 1907. The research revealed that the massif is similar to the Bushveld stratiform complex. Unlike other layered plutons, the Northern Saranovsky massif has a large amount of chrome ore bodies as compared to ultramafic host rocks. As many studies have shown, the chromitites of the Main Saranovskoe deposit are severely tectonized. The strike and dip of the ore bodies is complicated by numerous faults. These observations imply that the massif is a fragment of a large stratified pluton intruded into the Proterozoic metasedimentary unit. The fracturing reflects the massif intrusion conditions and provides new petrogenetic information on the relevance of our study of the tectonic fractures of the Saranovsky massif. Studies have been made on the fracture and furrow displacement orientations along the planes in the main ore bodies: western, central and eastern, within the two parts of the deposit. The local stress tensor has been reconstructed using the Angelier method in the Win-Tensor program. It has been stated that the chromitites studied contain 3–4 main fracture systems whose orientation varies together with the orientation of the ore bodies. The main compressive stress axis is oriented subvertically both in the central and southern parts of the deposit, and the main tensile stress axis forms an acute angle with the ore body contacts in the center of the deposit and is oriented subperpendicular to them in the southern part. It has been concluded that fracturing of the chrome ore bodies in the Main Saranskoe deposit took place during the massif motion into the upper crustal horizons with the subvertical orientation of the ore bodies remained unchanged. This casts doubts on the probability of formation of the Northern Saransky massif as a result of gravity differentiation of magmatic melt, since in this case the ore bodies should have undergone a vertical turn which is not exhibited by their fracturing.

Distributions of Platinum Group Elements and Re-Os Isotope Systematics in Chromite from the Coobina Chromitite Deposit in Western Australia: Implications for Chromite as a Sulfide Mineralization Indicator

ABSTRACTThe abundance of Ru in chromite has been suggested as an indicator of sulfide liquid saturation in komatiites. The komatiite magma-derived Archean Coobina intrusion is known to be barren in terms of sulfide mineralization. Therefore, the Coobina intrusion can serve as a useful case study to test the applicability of Ru abundance in chromite as a potential indicator for sulfide mineralization, as well as for better understanding the PGE-chromite association in general.The Coobina intrusion is a highly deformed layered intrusion interpreted to be a flared dike. It contains multiple massive chromitite seams that have been recently mined for metallurgical-grade chromite. In this study, 18 samples from chromitite seams throughout this intrusion are investigated for their whole-rock platinum group element (PGE) contents, which are compared to their chromite mineral chemistry (including PGE content), the platinum group mineral (PGM) mineralogy, and Re-Os isotope systematics. Each sample has a similar chromite major and minor element chemistry, but a unique trace element signature, even within the same seam. In general, there are higher concentrations of Ru (>300 ppb) within chromite in the southeast (toward the feeder dike) and lower concentrations (<50 ppb Ru) in the northwest. At a sample scale, Ru in the whole rock and Ru in solid solution in the chromite are inversely correlated, while Ir shows a positive correlation between the whole rock and chromite mineral chemistry, indicating differing partitioning behaviors within the iridium-group PGE (IPGE = Os, Ir, Ru). The inverse correlation between Ru in solid solution within chromite and Ru in whole-rock chromitite suggests that, for seams with high Ru in whole rock, Ru is occurring within separate PGM phases. This is supported by the observation that the samples with high whole-rock Ru also have a high number of visible metal alloy and/or PGM inclusions. Although these inclusions are not necessarily Ru-rich phases, their presence suggests that there is a preference for these samples to form nuggets, which may restrict Ru partitioning into the chromite crystal structure. We suggest that the low Ru values in the Coobina chromite are a result of transient sulfide saturation. The Re-Os isotopic composition of the Coobina chromitite is chondritic [γ187Os(3.189 Ga) = −0.63 ± 0.21] and is consistent with derivation of the Coobina parental magma from the convecting upper mantle source, providing evidence for the mantle origin of the Coobina PGE inventory.If using chromite as a detrital indicator mineral for magmatic sulfide exploration, it must be kept in mind that transient sulfide saturation within chromitite seams may give a false positive signature.

Direct production of Fe-Cr-Ni-Mn crude alloy from the mine waste by arc smelting process

ABSTRACT The utilisation of mine waste/low-grade ores has become a major concern for the mining and metallurgical industries. Day by day, high-grade ores are rapidly depleted and fines/low-grade ores are dumped in the mining site, becoming a source of pollution and taking up a lot of area. To overcome the above problem, a novel smelting reduction technology was directly used to utilise low-grade/mine waste as an alternative raw material for the production of crude alloy and further for stainless steel. In this work, Fe-Cr-Ni-Mn crude alloy was directly produced from the mine waste/ low-grade ores by a high-temperature arc smelting process. The dried composite pellets were prepared using chromite overburden (COB), chrome ore fines (Cr ore fines), and lean-grade manganese ore (LG-Mn ore) in the ratio 4:3:3 at a 500 g scale. The effect of slag basicity (0.1–0.8) on metal concentration and recovery was studied and optimised for maximum metal recovery (Fe, Cr, Ni, and Mn) in the direct smelting experiments. The Fe-Cr-Ni-Mn crude alloy having 71.6% Fe, 22.69% Cr, 1.02% Ni, 0.972% Mn, and 2.41% C at 0.4 basicity was successfully produced with a metal recovery of 63.1% at ∼1700°C.

Forecast of the morphology and occurrence conditions of complex chromite ore bodies (on example of Labogeyskoe-2 site, Polar Urals)

Background. Chromium ores are confined to stratified massifs of basic and ultra-basic composition. The Voikaro-Sinyinsky massif is part of the main hyperbasite belt of the Urals. Inside the hyperbasites of this massif, at the boundaries of tectonic flakes in particular, ultra-basic metamorphites are developed, constituting the zones of sharply variable thickness. During survey routes, a mechanical halo of scattering of ore fragments was found. When studying the ore stockpile, ditches opened the Labogeyskoe-2 chromite ore body, which belongs to the Pogureysky block of the Voikaro-Sinyinsky massif. In the ore occurrence area, harzburgites are predominantly developed with thin striped dunite aggregates in a small volume and individual dunite bodies of low thickness. Chromium ores are densely impregnated, medium- to coarse-grained. The amount of chromospinelides in the composition of ores сonstitutes 90—95%, the serpentine of irregular shape as well as the relics of olivine and emerald-green uvorovite grains, along with the single grains of pyrrhotite and magnetite are found in the interstitia (2—5%). Ores are massive, often cataclazed. The experience of studying this ore occurrence can serve as an analogue for a more effective study of similar ore occurrences. Aim. Evaluation of the Labogeyskoye-2 ore occurrence for the application of the information obtained and methods of its study in the study of a similar Levopayersk ore body, which will help save time and finances in the design and more efficient exploration.Materials and methods. During the filming routes, a mechanical halo of scattering of ore fragments was detected. During the study of the ore collapse in 1966, the KM22—KM25 ditches were passed and the Labogeyskoye-2 chromite ore body was uncovered by the KM24 ditch. In 2013, during geological exploration at Labogeyskoye-2, 3 ditches (K50—K52) were passed and detailed gravimagnetic studies of Institute of Mineralogy, Geochemistry and Crystal Chemistry of Rare Elements in 2011—2012 were performed.Results. The Levopayerskoe ore body is probably the closest analogue of the Labogeyskoye-2 ore occurrence among the 24 ore occurrences, for which geological plans and calculation sections were compiled based on the results of mining and drilling operations.Conclusions. The closest analogue of the Labogeyskoye-2 ore occurrence is probably the Levopayerskoye ore body. Therefore, further geological and exploration work at the Labogeyskoe-2 site should be carried out taking into account the conditions of occurrence of the similar Levopayerskoe ore body.

The development risk assessing of hypertension in underground workers during the psychological support

Introduction. For the purpose of studying the psychovegetative state, predictors of hypertension and the risk of its development, including in the age aspect, we have examined sixty underground workers of a chromium ore mining enterprise (the main group), whose working conditions belong to the classes 3.3-3.4. Scientists divided the main group into two subgroups: <45 years (n=20, age 38.45±2.95 years), and >45 years (n=40, age 50.90±1.46 years). The comparison group consists of 49 ground workers whose working conditions belong to the class 3.2. We formed two subgroups from the comparison group: 23 employees aged 38.0±2.8 years, (comparison group <45 years); and 26 employees aged 49.2±2.1 years, (comparison group >45 years). The study aims to research and substantiate the predictors of the development of hypertension of underground workers, depending on age and psychovegetative status. Materials and methods. Experts have investigated the state of the cardiovascular system by clinical, functional and laboratory diagnostics. We have investigated the psychovegetative status with an assessment of the level of neuropsychiatric tension, anxiety, attention, subjective reflection of psychovegetative distress. Results. Experts have identified the decreased attention (OR 7.50; 95% CI - 2.39-23.58), increased personal anxiety (OR 11.06 95% CI - 4.35-28.10) and an increase in the number of psychovegetative complaints (OR 22.50; 95% CI - 7.09-71.41) in the patient group with arterial hypertension syndrome. We identified the identified predictors of arterial hypertension in the analysis of ROC in the psychosomatic module: age >44 years, experience >15 years, number of psychovegetative complaints >1, increased serum uric acid >298 μmol/l, pulse pressure >41 mm Hg.st. The module confirms the inversion of psychovegetative adaptation into psychosomatic disorders with an increased risk of hypertension with increasing age. Limitations. The data obtained are specific to a specific group of miners, the methodological approach of this study can be used in other professional groups. Conclusion. When identifying a psychosomatic module, it is advisable to include employees in the risk group for hypertension. Within the framework of corporate programs for the preservation of health and the prevention of production-related diseases, it is advisable to carry out psychological support for employees of dangerous professions with the study of psychovegetative status. Ethics. The scientists have conducted research in compliance with ethical principles and with the voluntary informed consent of the participants.

A detoxification and value-added process for chromium ore processing residue (COPR) and Fe-C-bearing dust: Direct reduction-magnetic separation

Chromium ore processing residue (COPR), containing much virulent hexavalent chromium [Cr(VI)], is a by-product derived from chromate production. Fe-C-bearing dust from steel industry is very difficult to be utilized effectively because of its complex composition and unstable properties. The dust was co-processed with COPR by a direct reduction-magnetic separation process in this study. Through the strong reducing ability of solid carbon in Fe-C-bearing dust, the compounds of Cr and Fe were reduced to (Cr, Fe)7C3 alloy during the reduction roasting process and then selectively recovered by magnetic separation. In addition, the Pb and Zn compounds were reduced and volatilized into flue gas at high temperature. Under the optimal conditions, the results indicated that Cr-containing iron powder with 72.59 % Fe and 6.34 % Cr was obtained, and the recoveries of Fe and Cr were respectively 79.1 % and 76.9 %. The volatilization rates of Pb and Zn met 97.47 % and 99.95 %, respectively. The non-magnetic tailings were determined to be nontoxic and could be used as high-quality raw materials for building.

Research on the evolution of the global import and export competition network of chromium resources from the perspective of the whole industrial chain

As an important strategic mineral resource, chromium is essential for developing emerging industries. The high geographical concentration and increasing demand make the international trade of the global chromium resources industry face many competitions. Therefore, based on trade data from 2005 to 2019, this paper builds the original trade network and the derived competition network of import and export trade of the whole chromium industry chain, to analyze the evolution of the global competition relationships and provide a reference for the future global trading. The results showed that: (1) The competition varies at different stages. Upstream and middle importers and exporters are gradually becoming integrated, and the oligopoly trend is obvious; Downstream competition is becoming more and more fierce. (2) In the competitive trade network, China, USA, South Africa, India, and Kazakhstan have absolute competitive advantages and have substantial control and influence on the whole network. (3) The export competition between Asia and Africa runs throughout the whole industry chain; Asia, Europe, and North America run through the import competition of the whole industry chain. (4) The world's major exporters of chromium ore, are shifting from upstream-production enterprises to joint-producer of middle and downstream products such as ferrochromium. It shows a transfer trend of export competition from the upstream to the middle and downstream. The above analysis can help countries identify their trade competitors and provide suggestions for finding new partners.

Treatment of soda ash chromite ore processing residue by Waste-Molasses-Based Ball Milling: A new strategy for disposal of waste with waste

The current technology of soda ash Chromium Ore Processing Residue (COPR) detoxification consumes a large amount of acids (as in the wet reduction process) and requires high temperature, along with the generation of carbon dioxide (as in the dry reduction process), and thus, is not cost-effective and environmentally-friendly. Waste molasses (WM) is waste biomass consisting of various reducing sugars, a cost-effective reducing agent. According to the idea of treating waste with waste, this study put forward a ball milling + WM method to detoxify leached-soda ash COPR (e.g., dried COPR containing 1622 ± 28 Cr(VI)/kg). Through response surface experiments, it was determined that under the best conditions (i.e., the milling speed = 600 rpm, the milling time = 2 h, WM dosage = 7.5% of the dry mass of COPR, and the ball-to-powder weight ratio, BPR = 12), the reduction efficiency of Cr(VI) reached 98.35%. The Toxicity Characteristic Leaching Procedure (TCLP) total Cr concentration reached 1.82 mg/L, meeting the standard (total Cr < 5 mg/L) of the US Environmental Protection Agency (USEPA). The associated reaction mechanism was determined as: under the action of mechanical energy, the structure of Cr(VI)-embedded matrixes was destroyed, and the internal, otherwise non-exchangeable, Cr(VI) was exposed and underwent redox reactions with WM under alkaline conditions. In brief, WM-based ball milling to detoxify COPR is cost-effective and provides a new reference for the disposal of waste with waste.

Development and testing of a combined process based on the use of a flat-bottomed hydrocyclone and a multi-frequency screen

The article provides a brief overview of the development of technology and equipment for the preparation of finely disseminated ores of ferrous and non-ferrous metals for further processing. Fine screening processes and equipment for crushed ores are considered, including in combination with centrifugal hydraulic classification. The purpose of the work was to improve hydraulic screening performance and efficiency for crushed ores. In order to optimize the preparation of finely disseminated ores for processing, a combined preliminary hydraulic classification process was developed for crushed ores based on the use of a flat-bottomed hydrocyclone and a multi-frequency screen. A pilot plant was used to test the process. The article contains qualitative and quantitative performance indicators for the hydraulic screening of crushed chromium ore with a particle size of 300&ndash;0 &mu;m. The total recovery of all size classes below 300 &mu;m into the undersize of the multi-frequency screen was 86.42 % and the recovery of finer ore classes (below 150 &mu;m) was 91.09 to 92.97 %. The resulting combined process using a flat-bottomed hydrocyclone and a multi-frequency screen improves the total equipment performance, ensures high recoveries of fine classes into the undersize, extends the service life of fine sieves and reduces water consumption for oversize irrigation. This combined process is also recommended for use in hydraulic screening of magnetite concentrates at mining and processing plants in order to improve the iron content, as well as in closed fine grinding circuits in order to prevent overgrinding of valuable minerals and reduce the circulating load on the screens.

Sufficient extraction of Cr from chromium ore processing residue (COPR) by selective Mg removal

Chromium ore processing residue (COPR) is a hazardous waste generated during the production of chromate. Currently, approximately 10% of Cr2O3 cannot be extracted after chromite sodium roasting and remains in COPR, wasting valuable Cr resources. In this study, Mg was selectively removed by using (NH4)2SO4 roasting in combination with H2SO4 leaching. The results showed that the selective removal of 79.55% Mg from COPR could be achieved under the optimum (NH4)2SO4 roasting conditions (80 mmol (NH4)2SO4, 800 °C, 2 h). During the subsequent sodium roasting and acid leaching stages, the Cr extraction rate was 84.63% for the COPR direct roasting and 95.39% for the Mg removal residue roasting. The increased Cr extraction efficiency is attributed to the transformation of Mg-rich spinel and diopside (the Mg & Cr coexisting phases) in COPR converted into easily extractable (Fe,Cr)2O3 and Cr2O3 after the Mg treatment. This study investigated that the phase transformation of the Cr host phases is crucial for the sufficient extraction of Cr and provides inspiration for the development of efficient and practical Cr extraction techniques. Moreover, the method can be extended to the effective extraction of Cr from other Cr-containing wastes.

Magnetodielectric and low-frequency microwave absorption properties of entropy stabilised ferrites and 3D printed composites

High-entropy ferrites (HEFs) are a new group of high-entropy oxides with unique magnetodielectric properties that offer a wide array of possibilities for high-frequency applications. Various ions were introduced at octahedral sites in the spinel structure to test the role of the high-entropy structure's formation on its properties. The structural analysis confirmed the formation of single-phase spinel structure even for (FeCoNiMg)(FeCr)2O4 HEF. Dielectric studies showed that introducing Mg2+ and Cr3+ ions increased electrical conductivity and dielectric losses over a wide frequency range. Low frequency (from 0.8 to 1.5 GHz) studies showed that for (FeCo)Fe2O4 and (FeCoNi)Fe2O4 ferrites reflection losses (RL) are negligible, while for both (FeCoNiMg)Fe2O4 and (FeCoNiMg)(FeCr)2O4 ferrites RL higher than 90% were observed. The temperature dependence on the absorption properties was confirmed for (FeCoNiMg)(FeCr)2O4 HEF. The highest absorption window was observed for 343 K, for which RL higher than 90% appears from 1.25 to 1.5 GHz. The possibility of the 3D printing of microwave absorption composites from HEFs was also tested. It was confirmed that the addition of (FeCoNiMg)(FeCr)2O4 HEF drastically increases the absorption properties up to 85.5% at 2.72 GHz for the absorber with the same thickness as made from the pure acrylonitrile butadiene styrene (ABS). Interestingly, the EMI shielding properties of these composites are mainly related to the dielectric losses improved by the addition of entropy stabilised ferrites in 3D printed composites with various ferrite concentrations.

The influence of age, waist circumference and smoking on the respiratory function indices on the example of employees of a chrome ore mine

Introduction. Employees engaged in mining are exposed to several harmful (hazardous) occupation factors: dust factor, industrial noise, general and local vibration, hard labour, heating or cooling microclimate. The paper aims at studying the influence of the length of employment in underground chrome ore mining coupled with biological (age, obesity) and behavioral (smoking) parameters on spirometric bronchial obstruction indices. Material and methods. The study included 134 employees of a chrome ore mine having underground experience from 1 to 33 years. The comparison group comprised of 404 people who had never worked in a mine. External respiration function was evaluated using the Spirometer SP-1 (Schiller). Statistical processing was carried out using the SPSS 22. One-factor and multi-factor linear regression models were built. Results. The construction of one-factor linear regression models of the dependence of FEV1%, FVC% considering the selected independent factors (age, waist circumference, smoking experience, underground experience) showed a statistically significant effect on the dependent variable of all factors in the model (R2 = 0.010-0.135; p = 0.026-0.0001). The variability of obstructive parameters in a multi-factor linear regression model occurs not often in terms of the studied factors (as for FEV1%, R2 = 0.163; as for FVC%, R2 = 0.107). Smoking experience and waist circumference are the most significant factors leading to the decrease in these indices. Age and underground work experience are less important, but statistically significant. Limitations. The limitation of the results of the study was that they characterize a specific set of certain working conditions and lifestyles of workers in chromium mines. Conclusion. A small part of the impact on the obstruction indices of underground work experience might be due to the use of modern engineering systems to eliminate the harmful effects of occupation factors, as well as personal respiratory protection from dust exposure.

The Use of Olivine Mineral From Chrome Ore Enrıchment Process Wastes as Fillers in Asphalt Concrete

Bu çalışmada ferrokrom tesislerinde kromit cevherinin zenginleştirilmesi sürecinde ortaya çıkan atık olivin malzemesinin esnek üstyapılarda filler olarak kullanılabilirliği araştırılmıştır. İlk aşamada geleneksel kırmataş kalker agregası tozu kullanılarak elde edilen gradasyonda sabit filler oranı %4.7 olarak alınmış ve bitüm oranı %3,5, %4,0, %4,5, %5,0, %5,5 alınarak optimum bitüm yüzdesi elde edilmiştir. İkinci aşamada, ilk aşamada bulunan optimum bitüm yüzdesi ile geleneksel kırmataş kalker agregası tozuna %0, %25, %50, %75 ve %100 oranlarında olivin ikame edilerek oluşturulan numunelere; stabilite, akma, pratik özgül ağırlık, boşluk yüzdesi, asfalt dolu boşluk yüzdesi ve agregalar arası boşluk yüzdesi deneyi yapılmıştır. Elde edilen sonuçlara göre geleneksel kırmataş kalker agregası filler malzemesiyle ikame edilen olivin yüzdelerine göre asfalt betonunun mühendislik özelliklerinin değişimi karşılaştırılmıştır. Sonuç olarak olivinin sıcak karışım asfalt betonlarda filler malzeme olarak kullanılabileceği görülmüştür.

Diagenesis of clastic ores of the Ishkininо Co-bearing massive sulfide deposit (Southern Urals): Mineralogical-geochemical data and thermodynamic modeling

Research subject. The transformed clastic ores (ore diagenites) of the Ishkinino Co-bearing massive sulfide deposit hosted by serpentinites of the Main Uralian Fault Zone.Materials and methods. The structures and textures of the ores were stu died. The trace element contents of sulfides and oxides were determined using LA ICP MS. The physical and chemical modeling of the diagenetic formation of accessory As minerals was conducted using the Selektor program package. Results. The clastic ores are transformed gravelites with angular and rounded clasts of serpentinites, sulfides and chromite in the psammitic matrix of the same mineral composition. No hydrothermal minerals remain in gravelites; they are replaced by crystalline pyrite-2, porous pyrite-3, anhedral pyrite-4, pyrrhotite, chalcopyrite and magnetite. Chalcopyrite and magnetite replace all sulfides, sulfarsenides, chromite and gangue minerals. Chromite occurs as fragmented crystals or inclusions into serpentinite clasts. The matrix hosts euhedral cobaltite crystals with nickeline, gersdorffite and native gold inclusions. Crystalline pyrite-2 is characterized by higher Mn, Co, Ni, Cu and Zn contents. Porous pyrite-3 exhibits higher Co, Cu and Se contents. Anhedral pyrite-4 is enriched in most trace element contents in comparison with other sulfides and pyrite generations. Chalcopyrite is characterized by higher contents of Zn and Se. Pyrrhotite contains the highest Ni and hi gher Co contents.Conclusions. The main trace elements in the ores of the deposit (Co and Ni), as well as Cu, Zn and Mn, are hosted not only in sulfides, but also in oxides. Thus, chromite contains Zn and Ni, while magnetite contains Mn and Cu. Selenium occurs in all sulfides in similar quantities. Tellurium is mostly concentrated in pyrite-4. A comparative analysis of our results with those reported on other massive sulfide deposits showed that the serpentinite-sulfide gravelites of the Ishkinino deposit had been intensely transformed during diagenesis, which resulted in low trace element contents in diagenetic sulfides. The diagenetic alteration of clastic ores led to the formation of authigenic cobaltite, gersdorffite, nickeline and native gold as a result of trace element release from primary hydrothermal minerals. Thermodynamic mode ling showed the possibility of formation of As-bearing minerals (in particular, nickeline) at temperatures of 200°C and below.