Catagenetic type of manganese ores:REE and isotope(δ^(13)C,δ^(18)O)geochemical features(on the example of the Usa deposit,Russia)

Chemical(REE and major elements)and isotope(δ^(13)C,δ^(18)O)composition of carbonate manganese ores and manganese-bearing carbonates of the Usa deposit(Siberia,Russia)were studied.Received data on the composition of REE exhibit both the distinct negative(Ce/Ce*_(PAAS)<1)and positive(Ce/Ce*_(PAAS)>1)cerium anomalies and the positive Eu-anomaly(Eu/Eu*_(PAAS)>1).Negative Eu-anomalies are not observed.The contents of Mn,Fe,REE,and Ce-anomalies show a positive correlation with each other.Ce-anomalies and the amount of manganese and REE in relation to the carbon isotope composition(δ^(13)C)show a negative relationship and indicate that oxidized carbon of organic matter played an important role in the concentration of manganese and REE in manganese ores.The chemical and isotope composition of examined rocks indicates on secondary formation of Mnores.Two major phases and sources are distinguished in the ore-forming process characterized by diff erent chemical(REE and ore elements)and isotope composition:(i)highgrade manganese ores(with high contents of REE and light carbon isotope composition)and(ii)low-grade manganese ores(with low contents of REE and heavy carbon isotope composition).

Reductive leaching of manganese oxide ores using waste tea as reductant in sulfuric acid solution

Manganese oxide ores from Gabon and Xiangxi were leached with waste tea as reductant in dilute sulfuric acid solution. The effects of waste tea dosage, concentration of sulfuric acid, liquid-to-solid ratio, leaching temperature and reaction time on leaching process were explored. The leaching efficiency of Gabonese manganese oxide ore reached almost 100% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 2.5 molFL, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching efficiency of Xiangxi manganese oxide ore reached 99.8% under the optimal condition which was determined as follows： manganese oxide ore to waste tea mass ratio of 10：1, sulfuric acid concentration of 1.7 mol/L, liquid-to-solid ratio of 7.5：1, leaching temperature of 368 K, time of 8 h. The leaching process followed the internal diffusion controlled kinetic model, and the apparent activation energies of Gabonese manganese oxide ore and Xiangxi manganese oxide ore were calculated to be 38.2 kJ/mol and 20.4 kJ/mol, respectively. The morphological changes and mineralogical forms of the ore before and after the chemical treatment were discussed with the support of XRD analysis and SEM analysis.

Leaching of low grade zinc oxide ores in Ida^(2-)-H_2O system

Ida2--H2O system（iminodiacetate aqueous solution） was used to leach a low grade zinc oxide ore for Zn extraction.The effects of leaching time,liquid-solid ratio（L/S）,total concentration of Ida2-（[Ida2-]T）,leaching temperature and pH on Zn leaching recovery and the dissolution of impurities such as Ca,Mg,Cu,Ni,Fe,Pb and Cd were investigated.Results show that Ca,Mg and Fe in ores were hardly dissolved in alkalescent iminodiacetate aqueous solution,while valuable metals such as Cu,Ni,Pb and Cd were partly dissolved into leaching liquor with Zn.The recovery of Zn reaches 76.6% when the ores were leached for 4 h at 70 ℃ by 0.9 mol/L iminodiacetate aqueous solution with pH of 8 and L/S of 5：1.

Research status of carbonaceous matter in carbonaceous gold ores and bio-oxidation pretreatment

Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanide complex is robbed by adsorption of carbonaceous matter, which is similar to activated carbon in cyanide leaching of gold. The pretreatment methods of carbonaceous gold ores were introduced, including high temperature roasting, bio-oxidation, chemical oxidation, competitive adsorption, barrier inhibition and microwave roasting. Recently, bio-oxidation was developed rapidly due to its advantages such as mild conditions, simple processes, low energy consumption and friendly environment. The known microorganisms related with bio-oxidation pretreatment mainly are chemolithotroph bacteria such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The researches on decomposing and passivating carbonaceous matter were commenced by Phanerochaete chrysosporium, Pseudomonadaceae and Streptomyces setonii. Finally, the main problems were analyzed and the application prospect of this technique was looked forward.

Infrared thermography for prediction of spontaneous combustion of sulfide ores

The method of infrared thermography to predict the temperature of the sulfide ores has a large error. To solve this problem, the temperature of the sulfide ores is measured by thermal infrared imager and recording thermometric instrument contrastively. The main factors, including emissivity, distance, angle and dust concentration that affect the temperature measurement precision, are analyzed. The regression equations about the individual factors and comprehensive factors are obtained by analyzing test data. The application of the regression equations improves the precision of the thermal infrared imager. The geometric information lost in traditional infrared thermometry is determined by visualization grid method and interpolation method, the relationship between the infrared imager and geometry information is established. The geometry location can be measured exactly.

Manganese extraction by reduction-acid leaching from low-grade manganese oxide ores using CaS as reductant

The extraction of manganese from low-grade manganese oxide ores using Ca S derived from Ca SO4 as reductant was investigated. The effects of mass ratio of Ca S to ore, reduction temperature, reduction time, liquid to solid ratio（L/S ratio）, stirring speed, leaching temperature, leaching time and H2SO4 concentration on the leaching rates of Mn and Fe during the reduction–acid leaching process were discussed. The leaching rates of 96.47% for Mn and 19.24% for Fe were obtained under the optimized conditions of mass ratio of Ca S to manganese oxide ore 1：6.7, L/S ratio 5：1, stirring speed 300 r/min, reduction temperature of 95 °C for 2.0 h in the reduction process and leaching stirring speed of 200 r/min, H2SO4 concentration of 1.5 mol/L, leaching temperature of 80 °C for 5 min in the leaching process. In addition, this process can be employed in the recovery of manganese from various manganese oxide ores, and Mn leaching rate above 95% is obtained.

Dechromization and dealumination kinetics in process of Na_2CO_3-roasting pretreatment of laterite ores

A novel process was proposed for the activation pretreatment of limonitic laterite ores by Na2CO3 roasting. Dechromization and dealumination kinetics of the laterite ores and the effect of particle size, Na2CO3-ore mass ratio, and roasting temperature on Cr and Al extraction were studied. Experimental results indicate that the extraction rates of Cr and Al are up to 99%and 82%, respectively, under the optimal particle size of 44–74μm, Na2CO3-to-ore mass ratio of 0.6：1, and temperature of 1000 ℃. Dechromization within the range of 600–800 oC is controlled by the diffusion through the product layer with an apparent activation energy of 3.9 kJ/mol, and that it is controlled by the chemical reaction at the surface within the range of 900–1100 ℃ with an apparent activation energy of 54.3 kJ/mol. Besides, the Avrami diffusion controlled model with on apparent activation energy of 16.4 kJ/mol is most applicable for dealumination. Furthermore, 96.8%Ni and 95.6%Co could be extracted from the alkali-roasting residues in the subsequent pressure acid leaching process.

Self-heating tendency evaluation of sulfide ores based on nonlinear multi-parameters fusion

In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples （ore samples 1, 2, 6 and 9） are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is： sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results.

REE Geochemistry of Sulfides from the Huize Zn-Pb Ore Field, Yunnan Province: Implication for the Sources of Ore-forming Metals

REE abundances in sulfides from the Huize Zn-Pb ore field were determined with the ICPMS after preconcentration. The REE abundances in 26 sulfide samples （including pyrite, galena and sphalerite） are very low, with the ~REE ranging from 1.6×10^-9 to 166.8×10^-9. Their LREE/HREE ratios range from 7.6 to 98, showing LREE enrichment relatively. The JEu values are below 1, indicating that they were deposited from an Eu-depleted and reducing fluid-system. Similar to the ore-hosting carbonate strata, calcite separates from carbonate veinlets filling in the fractures or faults crosscutting the carbonate strata also show clear Eu-depletion. This indicates that the carbonate veinlets and their parent fluid was possibly sourced from the strata and inherited the REE geochemical features of the strata. Therefore, REE-geochemical characteristics of both the sulfides and calcites, which were deposited from an ore-forming hydrothermal system, are similar to those of carbonate strata, and strongly suggest that the ore metals were mainly sourced from carbonate strata.

Rb-Sr isotopic dating of sphalerite from the giant Huize Zn-Pb ore field, Yunnan Province, Southwestern China

The giant Huize Zn-Pb ore field in Yunnan Province, southwestern China, comprises the Qilinchang and Kuangshanchang deposits. The deposits are large in scale (more than 5 Mt of Zn and Pb) and high in grade (average grade of total Zn and Pb is 30%). Reported in this paper are the results of Rb-Sr isotopic dating of sphalerite from this ore field. Two precise ages (223.5±3.9 Ma and 226±6.4 Ma) have been obtained from two isochrons. These two ages are close to the reported ages of native copper mineralizations related to the Emeishan flood basalts in this region, which are 226 Ma to 228 Ma. Previous studies showed that the magnitude of uplift resultant from the Emeishan flood basalts is greater than 1000 m, indicating that the Kuangshanchang and Qilinchang deposits were formed during the same geological event and originated by fluid migration during uplifting resultant from the Emeishan flood basalts.

Partitioning properties of rare earth ores in China

The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, and the weathering crust type. Both the Bayan Obo rate earth ore and the Zhushan rate earth ore are a kind of mixed ore, consisting of basmaesite and monazite. Their rate earth partifionings are strongly enriched in light rate earths, where CeO2 is 50% and the light rate earth partitioning is totally over 95%. The Mianning rate earth ore as well as the Weishan rate earth is a kind of rate earth ore only having basmaesite. Their rare earth partitionings are also strongly enriched in light rate earths, in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rate earth ore, there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Longnan rate earth ore, which is strongly enriched in heavy rate earths, Y2O3 is 64.83%, and the heavy and light rate earth partitionings are 89.40% and 10.53%, respectively. In the Xunwu rate earth ore, which is strongly enriched in light rate earths, CeO2 is 47.16%, and the light rate earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttrium and rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%, respectively, which are mainly industrial resources of the middle and the heavy rare earths.

Ore-blending optimization model for sintering process based on characteristics of iron ores

An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to represent chemical composition, granulating properties and high temperature properties of iron ores. After the relationships between iron ore characteristics and sintering performance are established, the ＂two-step＂ method and the simplex method are introduced to build the model by distinguishing the calculation of optimized blending proportion of iron ores from that of other sintering materials in order to improve calculation efficiency. The ore-blending optimization model, programmed by Access and Visual Basic, is applied to practical production in steel mills and the results prove that the present model can take advantage of the available iron ore resource with stable sinter yield and quality performance but at a lower cost.

FAULT TREE ANALYSIS OF SPONTANEOUS COMBUSTION OF SULPHIDE ORES AND ITS RISK ASSESSMENT

A logic fault tree of mine spontaneous combustion of sulphide ores was built by the fault tree analysis (FTA) based on a lot of mechanism investigation of sulphide ore spontaneous combustion in more than ten mines and review of a great amount of relevant

Multi-scale impact crushing characteristics of polymetallic sulphide ores

The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer(MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower;on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.

Removal of phosphorus from iron ores by chemical leaching

Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.

Some basic properties of granules from ore blends consisting of ultrafine magnetite and hematite ores

Some basic properties of granules,including the granule size distribution,packed-bed permeability,and chemical composition of the adhering layer,were investigated in this study for four iron ore blends consisting of 5wt%,25wt%,and 45wt%ultrafine magnetite and 25wt%ultrafine hematite concentrates.The effects of varying the sinter basicity(CaO/SiO2 mass ratio=1.4 to 2.2)and adding ultrafine concentrates on the variation of the adhering-layer composition and granule microstructure were studied.Moreover,the effect of adhering-layer compositional changes on sintering reactions was discussed in combination with pot sintering results of ore blends.Increasing sinter basicity led to an increase in the basicities of both the adhering layer and the fine part of the sinter mix,which were higher than the overall sinter basicity.When the sinter chemistry was fixed and fine Si-bearing materials(e.g.,quartz sand)were used,increasing the amount of ultrafine ores in the ore blends tended to reduce the adhering-layer basicity and increase the SiO2 content in both the adhering layer and the fine part of the sinter mix,which will induce the formation of low-strength bonding phases and the deterioration of sinter strength.The adhering-layer composition in granules can be estimated in advance from the compositions of the-1 mm fractions of the raw materials.

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scan- ning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering mate- dais was unraveled. The results show that, as the SiO2 levels increase in the iron ores, the lowest assimilation temperature （LAT） decreases, whereas the index of fluidity of liquid phase （IFL） increases. Below 1.5wt%, Al2O3 benefits the assimilation reaction, but higher concentra- tions proved detrimental. Larger quartz particles increase the SiO2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the forma- tion of liquid-phase low-Al2O3-SFCA with high IFL and high-Al2O3-SFCA with low IFL, respectively.

Microwave-assisted reduction roasting–magnetic separation studies of two mineralogically different low-grade iron ores

The microwave-assisted reduction behaviours of two low-grade iron ores having a similar Fe content of 49wt%but distinctly different mineralogical and liberation characteristics were studied.Their performances in terms of the iron grade and recovery as obtained from statistically designed microwave(MW)roasting followed by low-intensity magnetic separation(LIMS)experiments were compared.At respective optimum conditions,the titano-magnetite ore(O1)could yield an iron concentrate of 62.57%Fe grade and 60.01%Fe recovery,while the goethitic ore(O2)could be upgraded to a concentrate of 64.4%Fe grade and 33.3%Fe recovery.Compared with the goethitic ore,the titanomagnetite ore responded better to MW heating.The characterization studies of the feed and roasted products obtained at different power and time conditions using X-ray diffraction,optical microscopy,vibrating-sample magnetometry,and electron-probe microanalysis explain the sequential reduction in the iron oxide phases.Finally,taking advantage of the MW absorbing character of the titano-magnetite ore,a blend of the same with the goethite-rich ore at a weight ratio of 60:40(O2:O1)was subjected to MW roasting that resulted in a concentrate of 61.57%Fe grade with a Fe recovery of 64.47%.

REE Geochemistry of VMS and SEDEX Ores in China

REE ratios and patterns for massive pyrite ore and massive cuprous pyrite ore ofthe Baiyinchang orefield are quite similar to those for quartz keratophyritic tuff and quartzalbitophyre of the same orefield. However, massive cuprous pyrite ore of the Ashele Cu-Zn de-posit is similar to basalt-diabase of the same district in REE geochemistry. Comparison of theChinese VMS ores with those from Rio Tinto, Spain and Que River, Australia, in REEgeochemistry has been made. REE ratios and patterns of bedded-massive and massive ores ofthe Changba-Lijiagou Zn-Pb deposit, the second largest SEDEX deposit in China are similarto those of their host rocks, the Qinling shales of Devonian age and the Changba adamellite.The three types of ore and their host rocks of the Dongshengmiao pyrite (pyrrhotite)-Zn-Pbdeposit have parallel REE ratios and patterns.

Bioleaching of low-grade copper sulfide ores by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans

The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.The experimental results show that the bacteria grow best when the temperature is(30±1) °C and the pH value is 2.0.The bacteria concentration is 2.24×107 mL-1 in this condition.It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows.The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%,respectively.Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.