Pretreatment Of Ore Research Articles

Rapid thermal decomposition of manganese ore using microwave heating

The present work attempts to investigate the influence of microwave heating on thermal decomposition and dissociation behavior of manganese ore. The manganese ore could be rapidly heated volumetrically to 1000 °C in 17 min by microwave heating, with an increase in manganese content of the ore from 30% to 40%. XRD patterns and thermodynamic analysis shows that the process of microwave heating could be divided into three parts, namely the decomposition reaction of MnCO3, Mn2O3 and CaCO3, respectively. Mn3O4 were obtained at microwave calcination temperatures higher than 577 °C. Based on the results, microwave heating can be applied effectively and efficiently for pretreatment of manganese ore.

Primary copper sulfides bioleaching vs. chloride leaching: Advantages and drawbacks

Currently the vast majority of the world's copper is obtained through sulfide mineral processing. Primary copper sulfides are the most economically relevant due to their abundance. Therefore, several technologies have been developed in order to achieve an efficient copper extraction from these types of copper sulfides. Among these developments, the hydrometallurgical options of bioleaching as well as chemical chloride leaching are prevailing for copper sulfides due to their good results at lab, pilot and industrial scale. However, comparisons are not available among technologies due to differences in scale and mineral/ore used in different studies. In this work, we have compared bioleaching and chemical chloride leaching technologies (including sulfuric acid-sodium chloride ore pre-treatment) for a mainly primary copper sulfide ore. This comparative analysis showed first that bioleaching and chemical chloride leaching work at completely different range of redox potential as expected. Hydrometallurgical iron balances indicated that chloride leaching and bioleaching have comparable iron recovery levels. Copper balances showed that bioleaching is significantly more advantageous than chemical chloride treatments in terms of leaching kinetics and final copper recovery. These advantages were correlated to different primary copper sulfides leaching mechanisms that are taking place during bioleaching. Altogether, these results showed major advantages of bioleaching over chloride chemical leaching for the industrial low-grade primary copper sulfide ores treatment.

Selection of electrohydraulic grinding parameters for quartz ore

Under analysis is electrohydraulic grinding of rocks under electric charge using nanosecond high-stress pulses to optimize ore pretreatment. A nanosecond high-voltage generator of pulses at a capacity to 500 MW is designed and tested. A flow-through discharge cell at a voltage to 550 kW is developed. The new method of mineral grinding is highly efficient and enables designing commercial plants for electrohydraulic rock processing.

Prospects for underground leaching in gold mines

The authors describe experiments on pretreatment of ore by injection of explosive gases before underground leaching of gold in mine conditions. It is shown that injection of explosive gases into opening micro-fractures enhances efficiency of underground leaching owing to microstructural transformation of ore containing dispersed gold.

Effect of fine slime on the choice of columbium ore pretreatment flowsheets

The article presents studies of slime formation in processing of Vishnevogorsk columbium ore. The slime formation criterion is assumed as the presence of size grades less than 50 and 5 µm estimated from modern laser granulometer data. The optimal methods and equipment for grinding are chosen depending on rate of slime formation in final products. The studies use centrifugal and rod mills. The rod mill assures the lowest rate of slime formation. Based on the experimental results, the columbium ore pretreatment flowsheet and special ore disintegration methods have been selected. The flowsheet uses crushing machines ensuring the highest rate selectivity—inertia cone crusher and the lowest rate slime formation during milling—rod mill.

Исследование прочностных свойств руды при проектировании циклов рудоподготовки

Исследование прочностных свойств руды при проектировании циклов рудоподготовки

Effect of <i>Phanerochaete chrysosporium</i> on Graphite Degradation during Pre-Treatment of Simulated Gold Preg-Robbing Ore

Abstract. In this study, the effect ofPhanerochaete chrysosporiumon graphite was investigated, and graphite was used as a substitute of elemental carbon in carbonaceous gold ores. Under the condition of optimum process, the fungal degradation rate of graphite reached to 13.49%, and the carbon content of graphite was decreased by 5.13%. XRD analysis indicated thatPhanerochaete chrysosporiumcould destroy the crystal structure of graphite. FTIR analysis indicated thatPhanerochaete chrysosporiumcould increase the number of aliphatic structures and oxygen-containing groups. The cyanide leaching gold tests showed thatPhanerochaete chrysosporiumcan decrease the preg-robbing capacity of graphite, about 9.52%. It indicated thatPhanerochaete chrysosporiumis an available microorganism, which was employed to pre-treat carbonaceous matter in carbonaceous gold ores to reduce the interference of gold cyanidation leaching.

Characterization of an iron oxy/hydroxide (gossan type) bearing refractory gold and silver ore by diagnostic leaching

A detailed characterization of an iron oxy/hydroxide (gossan type) bearing refractory gold/silver ore was performed with a new diagnostic approach for the development of a pretreatment process prior to cyanide leaching. Gold was observed to be present as native and electrum (6–24 µm in size) and associated with limonite, goethite and lepidocrocite within calcite and quartz matrix. Mineral liberation analysis (MLA) showed that electrum is found as free grains and in association with beudantite, limonite/goethite and quartz. Silver was mainly present as acanthite (Ag2S) and electrum and as inclusions within beudantite phase in the ore. The cyanide leaching tests showed that the extractions of gold and silver from the ore (d80: 50 µm) were limited to 76% and 23%, respectively, over a leaching period of 24 h. Diagnostic leaching tests coupled with the detailed mineralogical analysis of the ore suggest that the refractory gold and silver are mainly associated within iron oxide mineral phases such as limonite/goethite and jarosite-beudantite, which can be decomposed in alkaline solutions. Based on these characterizations, alkaline pretreatment of ore in potassium hydroxide solution was performed prior to cyanidation, which improved significantly the extraction of silver and gold up to 87% Ag and 90% Au. These findings suggest that alkaline leaching can be used as a new diagnostic approach to characterize the refractoriness of iron oxy/hydroxide bearing gold/silver ore and as a pretreatment method to overcome the refractoriness.

ESTUDO DO REAPROVEITAMENTO DO GÁS DE TOPO DE ALTO-FORNO A CARVÃO VEGETAL PARA REDUÇÃO DO FENÔMENO DE CREPITAÇÃO EM GRANULADOS DE MINÉRIO DE FERRO

The phenomenon of particle size degradation of minerals due to decreptation is presented as source of fines. In the present work, a study of iron ores decrepitation by employing a system of thermal pretreatment of iron ore was carried out reusing exhaust gases from a mini charcoal blast furnace located in the state of Minas Gerais. The experiments were carried out in two periods of seven days each one, where in the first period the pretreatment system was deactivated and in the second period was activated. The results showed an improvement in the burden permeability by the reduction of the granules decreptation when it was used the thermal pretreatment, reflecting in a increasing of production

Agglomeration and column leaching behaviour of goethitic and saprolitic nickel laterite ores

Processability of complex, low-grade nickel (Ni) laterite ores via heap leaching is very limited due to some intractable geotechnical and hydrological challenges such as poor heap porosity/permeability and structural stability. This work presents some investigations on laboratory batch drum agglomeration and continuous column leaching behaviour of saprolitic (SAP) and goethitic (G) Ni laterite ores as part of the quest for an effective ore pre-treatment process for enhanced heap leaching. As a focus, the effect of ore mineralogy/chemistry on the agglomeration and column leaching behaviour of −2mm (crushed from −15mm run-of-mine) G and SAP Ni laterite ores was examined. To produce ∼5–40mm agglomerates in<15min, the SAP ore required a higher H2SO4 (30wt.%) binder dosage compared with the G ore, although both ores displayed substantially similar, coalescence-controlled agglomeration mechanism. The resulting G agglomerates were more robust than the SAP ones based upon their compressive strength and acidic solution soak test measurements. However, over 100days of continuous column leaching, the structural stability of the SAP agglomerate bed was slightly greater than that of G agglomerates, reflecting a lesser slump of the former. The pregnant leach solution analysis revealed greater Ni/Co extraction rates from the SAP than the G agglomerates. Whilst the total mass of acid consumed per ton dry ore processed was greater for the SAP ore, the total kg acid per kg Ni extracted was markedly lower. Incongruent leaching of gangue minerals’ constituent elements (e.g., Fe, Mn, Mg, Al and Si) occurred and contributed significantly to the overall acid consumption. The findings show the relevance of agglomeration and column leaching tests for providing useful information for plant designing and optimization of Ni laterite heap leaching operations.

Recovery of Zinc during the Pre-Treatment of a Refractory Gold-Bearing Ore

Mesophilic bacteria were enriched from samples collected from acid mine drainages in La Carolina (San Luis, Argentina). Two enrichments, E1 and E2, showed suitable rates for iron or sulphur oxidation, respectively. Both enrichments were characterized by FISH analysis. They were mainly composed by Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans respectively. Studies with both, mixed and individual enrichments, showed biooxidation (measured as iron solubilisation) of a refractory gold-bearing pyrite ore from Hualilán (San Juan, Argentina). Pyrite and sphalerite were the main mineral species in the ore with 7% w/w and 8% w/w of iron and zinc and approximately 25 ppm of gold. Leaching experiments (2% w/v ore, 1.8 initial pH, 180 rpm and 30°C) were carried out with the addition of different alternative energy sources (6.67 g/L sulphur powder, 1 g/L ferrous iron, 0.02% w/v yeast extract). Redox potential, pH, ferrous iron concentration and total Fe and Zn were measured regularly. A 100% of iron leaching (after 28 days in the best experimental condition) was observed in some of the cultures. In other systems high zinc release was obtained (100% of dissolution after 28 days in the best experimental condition). Our results strongly suggest that under the correct operating conditions, biooxidation pre-treatment can be used to recover zinc as a subproduct of gold extraction from refractory ore.

Sulphidic refractory gold ore pre-treatment by selective and bulk flotation methods

In sulphidic refractory gold ores, fine gold particles may be highly disseminated and locked up in sulphide minerals such as pyrite and arsenopyrite. Hence, pre-treating processes are necessary to extract gold for further processing methods like cyanidation. In this paper, the selective and bulk flotation methods are considered as primary sulphidic refractory gold ore pre-treating options. The results show that it is impractical to remove arsenic (As) and antimony (Sb) from downstream processes by using selective flotation. It was observed that 22% of total Sb and 31.1% of As remained in the final tailings. In this case, 24% of gold was recovered in the initial stage of flotation. On the contrary, in the bulk method of flotation, which was aimed at maximizing the gold (Au) recovery, the maximum Au recovery of 90.6% obtained after 60min of flotation at the grind size with d80 of 146μm. The bulk flotation method as a pre-treating method resulted in the concentrate with less toxic chemical elements such as As and Sb.

The Oxidation Pretreatment of a Sulfidic Refractory Gold Ore with Pyrolusite

An attempt has been made to study the pretreatment of sulfidic refractory gold ore with pyrolusite. The influences of various parameters were studied to optimize the conditions. The optimum leaching conditions were pyrolusite/gold ore mass ratio of 3.0, H2SO4concentration of 3.0 M, temperature of 100°C, particle size of 45μm, stirring speed of 200 rpm. After the pretreatment, gold and silver were exposed, these made the extraction of the precious metal in the gold ore much easier.

Metallurgical processes for scandium recovery from various resources: A review

Metallurgical processes for scandium recovery from various resources are reviewed. Scandium is mainly recovered as by-product from residues, tailings and waste liquors in the production of other metals such as rare earths, uranium, titanium, tungsten, aluminium, nickel, tantalum and niobium. Bauxite and nickel laterite ores are proposed as the most promising scandium resources for its production. Currently, the methods combined with hydro- and pyro-metallurgical processes, including ore pre-treatment, leaching, solvent extraction, precipitation and calcination, are commonly used for scandium recovery. New technologies for scandium recovery such as selective leaching and solvent extraction are possible development direction in the future.

Avaliação de alguns agentes lixiviantes para a remoção do cobre contido em um minério complexo de ouro

Alguns minérios complexos de ouro e cobre apresentam a característica de possuírem elevados teores de cobre, inviabilizando a utilização direta do processo de cianetação para extração do ouro. Esse trabalho apresenta os resultados experimentais de uma rota hidrometalúrgica para o pré-tratamento do minério de ouro e cobre visando a maximizar a remoção de cobre e a viabilizar a etapa seguinte de cianetação. Foram realizados experimentos de lixiviação utilizando H2SO4, Fe2(SO4)3, H2O2, HCl, HClO4 e NH4OH. Entre esses ensaios, as melhores extrações de cobre - próximas a 50% - foram obtidas em experimentos com duração de 15 minutos utilizando ácido sulfúrico a 82 ± 2ºC e uma combinação de ácido sulfúrico e peróxido de hidrogênio a 25 ± 2ºC. Os resultados obtidos foram inferiores àquele percentual mínimo de extração de cobre (aproximadamente 95%) necessário para viabilizar economicamente a etapa posterior de cianetação para a extração de ouro.

Sulfuric acid leaching of Igarapé Bahia gold-copper ore for copper extraction — An ore pretreatment for gold recovery by cyanidation

The high copper grade in the Igarape Bahia (Brazil) gold-copper ore restricts the direct application of the classical cyanidation process. Copper oxide and sulfide minerals react with cyanides in solution, causing high leach-reagent consumption, raising processing costs and decreasing gold recovery. According to studies, a feasible solution would be to pretreat the ore to remove copper minerals prior to cyanidation. The goal of this experimental work was to study the conditions for the removal of copper from the Igarape Bahia gold-copper ore by sulfuric acid leaching, applying a statistical approach to the experimental design. By using the Plackett Burman method, it was possible to select the variables that exhibited the largest influence on copper extraction at the sulfuric acid leaching stage. These variables were leach solution temperature, stirring speed, sulfuric acid concentration in the leach solution and ore particle size. The individual effect of these variables and their interaction influences on the experimental response were analyzed by applying the replicated full-factorial-design method. Finally, the selected variables were optimized by the ascending-path statistical method, which determined the best leach experimental conditions for maximum copper extraction. The optimized leaching conditions resulted in a copper extraction of 75.5%.

Review of gold extraction from ores

Australia is now an important gold producer in the world. The nature of Australian gold production is briefly reviewed and the hydrometallurgy of gold extraction is considered. The choice of processing routes for free milling, complex and refractory ores is discussed. For free milling ores, cyanidation and recovery by the Carbon-in-Pulp/Carbon-in-Leach process (CIP/CIL) is the primary and proven treatment process. Copper containing ores are discussed in some detail as they interfere in the CIP/CIL process. Oxygen consuming and preg-robbing ores are also described. Five different classes of process options for pretreating refractory ores are considered in detail. These options include: ultrafine grinding; acid and alkaline pressure oxidation; and a variety of chemical pretreatments such as: Activox process, HMC process and Electrolytic oxidation process. In Australia, the two pre-eminent options for refractory gold ore pretreatment are roasting and biooxidation and this development is reported. The trial of pressure cyanidation of stibnite concentrates at the Golden Spec mine in Australia is described. Pyrolysis, the Nitrox/Redox process, the Artech/Cashman process and the Caro's acid process have not gained commercial status so far. The potential for resin-in-pulp (RIP) to replace CIP/CIL is discussed. The use of cyanide has generated environmental concerns because of its toxicity and therefore research on alternative gold recovery processes using non-toxic reagents is considered. The key candidates are: ammoniacal thiosulphate, thiourea and halide solutions. The chemistry of these leaching systems is briefly described and proposed flowsheets are referenced. The future prospect for biohydrometallurgical gold recovery is indicated.

Pretreatment of chalcopyrite ore with alkali: A simple technique to improve the leaching mediated by thiobacillus ferrooxidans

A simple method to promote the extraction of copper and iron from chalcopyrite ore using the bacterium Thiobacillus ferrooxidans is reported. The method involves prior treatment of the ore with alkali. The alkali treatment also altered the rate of iron precipitation during the leaching process. An alteration of the microenvironment caused by removal of any inhibitory gangue material is suspected to be the reason for the observed improvement in the leaching rate. The alkali wash method may be a more efficient substitute for “ore regrinding”, the technique suggested by Torma [1] for removal of the inhibitory effect of a passivation layer that prevents further microbial attack onto the ore surface.

アンモニア加圧浸出法による含Niラテライト鉱石からのNi回収に関する研究

Some experiments on the recovery of nickel from laterite ore by the ammonia pressure leaching have been carried out in the current investigation. Hydrogen was used as the reducing gas, and ammonia solution containing ammonium sulphate was used as the leaching solution for the recovery of nickel from the reduced ores. The experimental results obtained are summarized as follows;(1) It is required for the efficient extraction of nickel that laterite ores are reduced with H2 gas at the rate beyond the critical flow rate during the reducing roasting, because the amounts of nickel oxides contained in laterite ores are very small.(2) The leaching rate of nickel by the ammonia pressure leaching is about sixteen times greater than that by of the atmospheric ammonia leaching.(3) The ammonia solution containing ammonium sulphate is more effective than that containing ammonium carbonate to obtain the leached solution without ferric ions.(4) The extraction of nickel exceeds 90 percent when the experiment on the recovery of nickel from laterite ore was carried out under the following reduction and extraction conditions: reduction temnerature 900°C, the flow rate of H2 gas 200cc/min, reduction time 90 min, leaching temperature100°C, oxygen pressure 2kg/cm2, stirring rate 500rpm and the concentration of ammonia and ammonium sulphate 3mol/l and 1mol/l, respectively.(5) More satisfactory pretreatment of laterite ore for the pressure leaching is attained by the reduction with H2 gas than by that with CO gas, which was descrided in our previous paper, because the extraction of nickel by the ammonia pressure leaching is not affected by the metallic iron formed during the reducing roasting.