Characterisation of buildup in an electric furnace for smelting copper concentrate

The results from a characterisation of buildup in an electric smelting furnace for treating copperrich feed material at the Boliden Ronnskar smelter in Sweden are presented. The aim of the work was to obtain better knowledge about the mechanisms behind the formation of the buildup. Samples from the buildup were taken during the rebuilding of the furnace. The samples were characterised using chemical and mineralogical techniques. The buildup consists mainly of different phases such as spinel, matte, olivine and metalloids and has a complex and varying mineralogy, which indicates that the buildup is not formed under equilibrium conditions.     

Mineralogy and geochemistry of Greek and Chinese coal fly ash

In this paper the mineralogy and geochemistry of Greek and Chinese coal fly ash are examined. Annual production of fly ash in China is around 160 Mt while in Greece lignite fly ash accounts around 10 Mt. Even though the mineralogical and chemical composition of the fly ashes coming from these two countries differs, there are common questions on the utilization of this material. The variation of the Greek fly ash’ chemical composition, from Ca-poor to Ca-rich fly ash, has resulted to applications such as dam construction, use in cement and possibly in concrete and road construction. The Chinese fly ash, which is rich in mullite, is broadly applied for brick making.     

The pore solution phase of carbonated cement pastes

Samples of hydrated cement pastes were exposed to atmospheres with various carbon dioxide concentrations at relative humidities controlled by different saturated salt solutions. When carbonated throughout their thickness, as indicated by the phenolphthalein test, they were resaturated with water and subjected to pore solution expression and analysis. The effects of the various carbonating environments on the pore solution composition and on aspects of the pore structure and mineralogy of the carbonated products are reported. Implications regarding the likely effects of different accelerated carbonation regimes on the corrosion behaviour of steel in concrete are discussed. In particular, it is shown that the use of saturated sodium nitrite solution to control the relative humidity of atmospheres with high concentrations of carbon dioxide may cause an evolution of gaseous oxides of nitrogen, which can result in the contamination of the pore solution with nitrite and nitrate salts.     

广西凤凰山锰银氧化矿的工艺矿物学特征

凤凰山锰银氧化矿石的锰矿物主要为隐钾锰矿，少量软锰矿和锰铅矿。银的赋存形式较为复杂，但大致可分为3种：①呈微细粒的角银矿、自然银、硫铜银矿和辉银矿等独立银矿物；②呈类质同像赋存于隐钾锰矿中；③呈微粒矿物包体分布于隐钾锰矿或褐铁矿集合体的微裂隙中。银的3种赋存形式的分配比例与矿石中隐钾锰矿的含量有关。软锰矿和锰铅矿基本不含银。     

Characterisation of non-sulphide zinc deposits using QEMSCAN®

Non-sulphide zinc deposits are important potential resources of zinc and other metals, which require accurate characterisation of the mineralogy, texture and grade for successful processing. The mineralogy of these deposits has traditionally been examined using optical microscopy, cathodoluminescence, XRD, SEM and EPMA. This study develops QEMSCAN® technology to rapidly acquire spatially resolved mineralogical data from non-sulphide zinc ores from Accha (Peru) and Skorpion (Namibia). The resulting modal and textural data provides significant additional information on the distribution of the ore minerals including detail on the trace minerals, grain size distributions, and mineral associations. The data were verified by XRD to assess clays and compositionally similar mineral polymorphs and EPMA to accurately establish mineral compositions. The detailed mineralogical knowledge from this study improves the lithotyping of the deposits and will benefit the ore processing strategies for these complex deposit types. The particular processing implications include assessments of the acid consumption, the abundance and distribution of penalty elements, and potentially low zinc recoveries relating to iron oxyhydroxides and sauconite.     

Rheological behaviour of lateritic smectite ore slurries

The characterisation and rheology of several nickel laterite smectite ores and pure minerals are compared to assess the effect of mineralogy and particle size on the viscosity of high pulp density slurries. A vane viscometer was used to determine the “optimum pulp density” (OPD) that gave a yield stress of 100 Pa which is considered to be optimal for pumping slurries into autoclaves in the HPAL process. In general, slurries containing finer particles were more viscous and smectite slurries exhibited poor rheological behaviour as compared to slurries of goethite < kaolin < talc < hematite < maghemite < magnesite. Blending the smectite ores with a fraction of the pure minerals improved the rheological behaviour of the pulp and can increase the optimum pulp density of the smectite blend by over 5% w/w.When the physical properties of the smectite ore and slurry were examined, a very good linear correlation was obtained between the optimum pulp density and the settling density which provides a simple measure of predicting rheological behaviour of slurries. The variation in the viscosity of the nickel laterite ores depends largely on their mineralogy and particle size distribution. The mean particle size and P₈₀ values of various smectite ores containing the same mineral phases were also found to have a reasonably good linear correlation with OPD in saline water, but the correlation of ore surface area with OPD was a poorer fit.     

Environmental Mineralogy Of Soils Around Selebi Phikwe Nickel-Copper Plant,BOTSWANA

This study determined mineralogical changes in soils as a result of mining and smelting of nickel-copper (Ni-Cu). Soil samples obtained around the Selebi Phikwe Ni-Cu plant, Botswana were studied using petrographic microscopy and X-ray Powder Diffraction (XRPD) technique. Bulk soil samples contained actinolite, albite, quartz, microcline, pyrrhotite, silicon sulfide and cobalt oxide, whereas the <2?μm fraction was made of kaolinite, illite, smectite, anorthite and quartz. Heavy minerals fraction of soil samples ranged between 5?wt% and 43?wt% with higher values occurring at sites close to either the mines or the smelter plant. Cobalt oxide and silicon sulfide identified in surface soils are indicative of mineralogical alteration of mining waste deposited on soils. Consequently, aspects of pollution management such as phytoremediation and phytomining, and environmental desulfurization could be introduced as pollution control measures at Selebi Phikwe.     

Variation of kerogen content and mineralogy in some Australian tertiary oil shales

Oil shale is a potential alternative source of petroleum products. The processes of retorting oil shale and refining shale oil are both affected by the composition of the parent rock. Mineralogical and geochemical data obtained from two bore holes in Queensland oil shale deposits are presented and discussed here. The data includes the variation with depth of mineralogy, ash content, moisture content and kerogen content. A strong correlation of hydrogen and organic carbon, and higher H/C ratios suggest that organic matter is present mainly as aliphatic compounds. Pyrite was identified as the major source of sulphur. This may provide some possibilities for easier removal of sulphur before the oil shale is processed.     

SYMMETRY: an interactive graphics computer program to teach symmetry recognition

SYMMETRY is a computer program that will draw two-dimensional motifs and patterns on the screen of a cathode-ray-tube (CRT) terminal. The program enables users to test for the presence of symmetry elements in these patterns by superimposing rotated, reflected, or glide-reflected patterns on the original.     

A correction procedure for the effects of inclusions on electron probe microanalyses of fine-grained materials

Spatial resolution limits frequently do not permit the complete separation of fine-grained phases in the analysis by electron probe techniques. A general correction procedure based on iterative regression is presented, which removes the effects of such contamination and results in good approximations of the pure phase compositions. An interactive FORTRAN code (PURGIT) implementing the described method is listed in the appendix. Applications of that procedure and its limits are discussed using: (1) specially designed numerical test-problems, and (2) some actual examples from experimental petrology.