Search Documents

By A. Kapoor

Gold mill effluents contain toxic pollutants such as cyanide (CN), thiocyanate (CNS), ammonia (NH4-N), and a variety of toxic metals. Various practical and economical technologies are in use for the removal of CN and toxic metals from gold mill effluents, however, the removal of CNS and NH4-N is challenging. The presence of CNS and NH4-N may make effluents toxic to aquatic life. The new Canadian Metal Mining Effluent Regulations will require mine effluents to be nontoxic. As a result, there is a need to develop practical and economical technology for CNS and NH4-N removal. The Mine Effluents Program in the Environment Group is presently evaluating biotechnology processes for the removal of CNS and NH4-N from gold mill effluents. The processes being evaluated are attached growth systems such as a Rotating Biological Contactor (RBC) and completely mixed suspended growth systems such as a Sequencing Batch Reactor (SBR) operating in a batch mode. The research to date at MMSL has shown that the RBC is very effective in removing CNS and NH4-N from simulated effluents. The NH4-N removal project showed that the RBC is capable of removing 0.8 g NH4-N/m2 of RBC disk area per day at an average temperature of 4.5 oC and hydraulic loading rate of 0.02 m3/m2/d. The RBC was also found to be very effective in removing CNS (feed = 200 mg/L and effluent < 1 mg/L) at 8 oC and a hydraulic loading rate of 0.02 m3/m2/d. The SBR was effective in removing CNS and NH4-N (generated from CNS degradation) at SBR operating conditions of two-12 h treatment cycles and a temperature of 12 oC. The end product of CNS and NH4-N oxidation was NO3-N, which is relatively non-toxic.

Nov 1, 2002

By S. Kelebek

Batch flotation tests were carried out using samples from stockpiles that were up to 1.5 months old as well as fresh samples oxidized in the lab for up to six months. Head grades and size distributions of samples were equalized whenever possible. The samples from stockpiles and oxidation experiments produced inferior nickel grade-recovery compared to the fresh sample. The poorer grade-recovery performance was attributable to two factors. First, a significant dilution effect was observed due to complete flotation of pyrrhotite. Secondly, the same stockpiling conditions caused nickel losses that were attributable to non-floatability of some pentlandite. Application of a high pH of 10 compared to the regular pH of 9.2 slowed down pyrrhotite flotation kinetics, but was not able to prevent complete flotation after 8 minutes. The samples oxidized in the lab did not match full characteristics of stockpile samples. They provided somewhat better selectivity for pentlandite. Some correlations were observed on a qualitative basis between surface characteristics such as elemental sulphur formation, activation and flotation behaviour. Oxidation conditions, which induce floatability on pyrrhotite while causing incremental loss in pentlandite floatability appear to be the root cause of difficulties in the processing of oxidized forms of these ores.

Jan 1, 2006

By Y. O. Fortier

"ForewordTHE Arctic Archipelago and northern Greenland contain an orogenic region that is as much as 300 miles wide and over 1,400 miles long. It occupies much of what was formerly classified with the Arctic Plains and grouped with other plains and lowlands of Canada as one main geological division. It is proposed that this folded region be designated the Innuitian Region and be recognized as one of the main geological divisions of Canada.Canada's main geological divisions (see Geological Survey of Canada, 1947) have been considered as consisting of a central shield, largely surrounded by plains that separate it from eastern and western mountains. The plains include the Interior Plains, the St. Lawrence Lowlands, the Arctic Plains or Low-lands, and the Hudson Bay Lowland, which is in the central part of the Shield. Plains and mountains are, strictly speaking, physiographic terms, but because mountains are generally folded regions and plains are generally made of undisturbed strata, such terms are useful vehicles to express the fundamental make-up of the land. Nevertheless, it is preferable to use the terms Appalachian and Cordilleran 'Regions' rather than 'Mountains', as those geological divisions are not exclusively made of mountains.Because of the lack of more definite information, the 'Arctic Plains' have included, in the past, regions with plateaux two to four thousand feet above the nearby sea, mountain ranges reaching approximately 10,000 feet above sea level, and regions of folded strata."

Jan 1, 1955

By R. Q. Honaker

It has been shown that naturally hydrophobic carbonaceous materials such as coal and graphite can be selectively coagulated and separated from hydrophilic impurities without using oily agglomerants, flocculants or electrolytes. The coagulation occurs at C-potentials significantly higher than those predicted by the classical DLVO theory, suggesting that it is driven by the hydrophobic interaction. In the present work, the energy barriers for the coagulation of a hydrophobic coal sample have been calculated using the extended DLVO theory which incorporates the hydrophobic interaction energy in addition to the dispersion and the electrostatic energies. For the coagulation of minerals present in the coal, the classical DLVO theory has been used for the energy barrier calculation. The results of these calculations provide an excellent correlation with the results of a series of Selective Hydrophobic Coagulation (SHC) tests conducted with run-of-mine coal and graphite samples.

Jan 1, 2004

By L. Jones, S. R. Lawrence, A. R. Holloway

Whilst dense medium separation is best known for its ability to concentrate diamond and coal deposits, the process is now being employed in southern Africa as a pre-concentration step to improve the economics of platinum group metal and nickel ores. DMS plants built for these industries (such as the 1600tph unit at Tati Nickel, Botswana), are spearheading an expansion in this area by reducing mine and process operating costs yet maintaining economic metal recoveries. This paper provides an overview of DMS technology and examines the economic benefits available to North American operators and projects, with recent case studies as reference.

Jan 1, 2009

By T. Schmidt, H. Assadi, F. Gartner, H. Kreye

Among all spraying processes, cold spraying has attracted a special attention in recent years, both as a coating - and more recently - as a rapid manufacturing technique. The interest in this process is mainly because of the fact that the deposition of spray material takes place at moderately low temperatures, and thus, oxidation and unfavourable microstructural changes can be alleviated. In this process, a highly compressed gas, flowing through a de Laval nozzle, accelerates the particles of the spray powder to high velocities of up to 1200 m/s. Although there is no melting of particles prior to impact on the substrate, cold-sprayed deposits can be denser and more tightly bonded as compared to the equivalent deposits produced by conventional thermal spraying methods. The present contribution focuses on this unique aspect of cold spraying. Modelling of particle impact, combined with various experimental observations, is employed to illustrate that bonding of particles and hence material deposition occurs through shear instability - associated with severe plastic deformation and localized heat generation - at the interacting surfaces of particles and substrate. The results of modelling also provide an insight to the influence of material and process parameters on the critical velocity and on the microstructural properties of cold-sprayed deposits.

Jan 1, 2006

By Gary Pattrick

A new class of spongy Au catalysts is studied for the selective catalytic reduction of NOx by propene under leanburn conditions. The spongy catalyst is an unsupported powdered Au that consists of micrometer particles (~5 microns) that have nanometer scale (~10 nm) internal skeletal structures. The effects of alloying 1 ? 50 atom % platinum group metals (M= Pt, Pd, Rh) and 5 wt% first row transition metals (M = Ti, Mn, Fe, Co) were studied. Even low additions of PGMs (1 at.%) cause significant shifts to lower temperature regions of activity and the largest shift is obtained for Rh. For Rh this is interpreted as a strong synergistic interaction between Rh and Au. Possibly related to the Rh effect, Co is the only other metal studied that lowers the temperature of NOx reduction. The other first row transition metals inhibit the reduction reaction.

Oct 1, 2003

By L. H. Bergmann

THE blasting practices described are fairly representative of those employed in the coal mines of Eastern Canada. As such, they may be of interest to Western Canadian coal mine operators. The treatment of the subject is general, no attempt being made to discuss blasting operations at any particular coal mine in detail. All the mines dealt with are mining bituminous coal and are classified under the Coal Mines Regulation Act of the Province of Nova Scotia as &apos;closed light&apos; mines. As such, they are required to use only &apos;permitted&apos; explosives and to apply them in a &apos;permitted&apos; manner, except where authority is given by the Mines Department to do otherwise.

Jan 1, 1945

By J. W. Gregg, P. M. Dranchuk, D. L. Flock

"From preliminary investigations it has been observed that although evaporation losses may be estimated by comparing single values of certain physical properties of crude oils and their evaporation residues, such techniques possess little accuracy unless both the evaporation process and the variation of the property as a function of the process are completely known. The accuracy of estimation may be increased somewhat through the comparison of property mid-per-cent curves. Further increases in accuracy are possible if bottoms yield •curves rather than mid-percent curves are used. The use of both the mid-percent and bottoms yield curves however involves a prohibitive amount of effort in most cases. Examinations of distillation bottoms from Hempel type distillations carried to end points just short of the cracking point have indicated that these bottoms are not appreciably affected by the evaporation process. It was further observed that bottoms of identical API gravity, obtained from a crude oil and its evaporation residues behave as if they were pure components which were unaffected by evaporation. Based on these observations Hempel distillation bottoms of equal API gravity were obtained for a crude oil and its various evaporation residues from API gravity bottoms yield curves. The volume percent of these bottoms in the crude oil and its residues were used to calculate the evaporation losses suffered by the crude in order to yield the various residues. The results indicate that, although further refinements in technique are required, it is possible to calculate evaporation losses with an accept-able degree of accuracy through the use of this method."

Jan 1, 1960

By P Hulteberg

In this article, an integrated catalytic reactor design approach to produce PEMFC-quality hydrogen is evaluated. The design is based on a high level of heat exchanging perfonned internally, highly active noble metal catalysts and a woven wire mesh catalyst support system. It consists of an integrated steam refonner and a catalytic burner section, a water gas shift section and a preferential carbon monoxide oxidation section. The reactor design is described and experiments perfonned to evaluate the two reactors built are reported. The two reactors have a maximum output of 3 Nm and 10 Nm3 hydrogen/h respectively. In the larger unit, a total of six fuels, three gaseous (methane, natural gas and liquid propane gas) and three liquid (naphtha, ethanol and methanol), were evaluated. The larger unit was also used to investigate how variations of parameters such as steam-to-carbon ratio in the steam reforming part of the system and the relation between oxygen and carbon monoxide in the preferential carbon monoxide oxidation affect the reactor perfonnance. The smaller unit was used, after implementing automatic control, to run a system life time test for 480 h. The refonner system perfonned according to specifications on almost every aspect.

Jan 1, 2005

By Dirige. A. P. E.

A study was conducted for an operating mine to determine the appropriateness of its tailings material to be used for the preparation of a low modulus, high density backfill. The research was initiated due to issues arising from increased observations of compressive failure of backfill placed in stopes and inconsistent backfill behaviour (i.e. increased backfill brittleness and modulus). Backfill materials investigated were classified tailings and de-slimed tailings. Characterization of the physical properties of the classified and de-slimed tailings materials was conducted to assess the effect that these material properties would have on the strength and deformation behaviour of high density backfill products made using them. Such behaviour was investigated to determine whether differences in tailings physical properties would influence the strength and modulus character of the backfill materials. Uniaxial (UCS) and consolidated-undrained triaxial compression strength tests were conducted to determine strength performance and deformation behaviour of backfill. This paper presents the results of the backfill material characterization study and how different particle size distributions affected the strength performance and deformation behaviour of the different backfill mixes. It also demonstrates how stress-strain curves generated from material strength tests were used to evaluate variation in high density backfill mix response when such materials were subjected to unconfined and confined (triaxial) compression loading.

Aug 1, 2013

By Dean Gerhardt

Why the need for proactive loose detection? ?? Past history of ground falls in Saskatchewan mines prompted research into new techniques for ground control. ?? Traditional tools for ground assessment (i.e. visual inspection, sounding with scaling bars) are not proactive and can often be time consuming. ?? Need existed for a system that was non-evasive, time efficient, and could be managed by a single operator. Ground Penetrating Radar (GPR) immerged showing the greatest potential.

May 1, 2008

By Glen Robertson, Jeff McLaughlin

"The Clarabelle Mill rock tailings have the potential to generate sulphuric acid through chemical and biological oxidation of sulphide minerals. Current rock tailings assay between 0.80 -1.40 %S, with sulphur occurring principally as coarse pyrrhotite. Acid generation within the tailings area can be substantially reduced by segregating pyrrhotite rich tailings in a submerged storage area and by depositing only low sulphur rock tailings in exposed areas. Laboratory tests confirmed that low sulphur tailings could be produced by flotation at reduced pH with a small xanthate addition. A plant test was conducted to evaluate the production of low sulphur tailings in conjunction with INCO's continuing commitment to environmental protection and progressive decommissioning of the metallurgical site.During the plant evaluation, approximately 5% of the mill rock tailings were reprocessed in a line of 100 tt3 Denver flotation cells. Tailing grades below 0.40% S were easily achieved through operation at pH 6 -7, with xanthate addition (dosages up to 0.02 lb/ton) and 10 -15 minutes of nominal retention time. Froth depths between 1 -3 inches combined with relatively liberal amounts of frother were required to pull the lightly mineralized froth into the concentrate which averaged 11% sulphur and less than 5% mass recovery. In addition, three field lysimeters were each filled with two hundred.ton bulk samples of low sulphur tails (0.35% S), standard rock tailings (0.98% S), and mill total tailings (2.30% S) for long term monitoring. The implications for full scale plant design, tailings area decommissioning, the possibility of increased nickel recovery and preliminary field lysimeter data are discussed."

Jan 1, 1994

By John W. Korczak

The use of geological and grade block models has been standard practice in mine design for many years now, with a wide range of software available for creation and analysis. Although geotechnical parameters are of vital importance to mine planning there is very little in the way of commercially available systems for integrating geotechnical data into the mine planning and design process. Sirovision is a new technology developed by the CSIRO (Commonwealth Scientific and Industrial Research Organization) in Australia for automated, safe and accurate 3D mapping of geological and geotechnical features. Datamine has integrated this capability into its product range so that Sirovision has become an integral part of the day-to-day mapping, mine geology and geological / geotechnical modeling in both open pit and underground mine environments. This is the first integrated underground application of Sirovision from Datamine collaboration with Xstrata Nickel at the Nickel Rim South Project. This paper discusses the role of Sirovision in collecting the raw data required for geological and geotechnical analysis and the interpretation in a quick, safe, auditable and reproducible manner.

May 1, 2009

By D. J. Houlahan

ABSTRACT Sorting has the potential to massively improve the pro?tability of mining base metal, hard-rock ores. However, several barriers to the increased application of sorting have been identi?ed, including a lack of mineral-speci?c sensors available to the industry. This paper presents the outcomes of acollaborative project to develop an induction-balance sensor speci?cally for low-grade copper and nickelores. A review of the basic principles of induction-balance sensing and of the sensor-rock interaction is presented. Early development and testing of the sensor on ores from the Thompson nickel belt in northern Manitoba is discussed. Shortcomings of the prototype identi?ed in early testing have now been over-come, leading to improvements in design and construction, as well as sensor accuracy. The improve dsensor has now been tested on additional ores from the Sudbury Basin, with good results. A discussion of potential applications is presented and recommendations for future development are made.

Jan 1, 2010

By M. Dotto, T. G. Joseph, M. Curley

"Equipment selection is a key decision in mine planning. Equipment size affects decisions from pit size to the total operation cost. Particularly when replacing haulage fleets for long-life surface mining operations, mining operations focus solely on haulage productivity. Road width and specifically ramp width are significantly affected by an increase in hauler size in terms of overall strip ratio through required highwall set-backs or sterilizing of lower ore access due to required overlying ramp fill structures. In addition, in light of ever increasing regulatory and reporting emissions requirements, bigger equipment may not translate into lower emissions per tonne moved. This study analyzes hauler-scale impacts on aspects not currently incorporated into conventional mine planning, including expansion of roads to accommodate larger equipment, road layer thickness variation depending on hauler size, and fuel consumption and emissions. Results indicate that such relationships have a large impact on cost. Therefore, an expanded consideration of the capacities of increasing equipment size in mine planning is highly recommended. ¦ KEYWORDS Equipment selection, Grade resistance (GR), Haul road, Haul truck, Mine planning, Payload, Rolling resistance (RR), Total resistance (TR) RÉSUMÉ La sélection du matériel est une décision importante dans l’aménagement des mines. La taille de l’équipement a une incidence sur la prise de décisions, depuis la taille de la fosse jusqu’aux coûts totaux des activités. L’exploitation minière se concentre uniquement sur la productivité des moyens de transport, particulièrement lorsqu’il s’agit de remplacer les parcs de camions de transport dans les exploitations à ciel ouvert à longue durée de vie. La largeur des routes, et spécifiquement la largeur des descenderies sont considérablement affectées par une augmentation de la taille des camions de transport en termes du coefficient global de recouvrement qui dépend de la taille requise des parois (si les descenderies sont agrandies, les parois devront être creusées de haut en bas afin d’agrandir la taille du fond de la fosse). Il faut aussi pouvoir procéder à l’excavation des gradins les plus profonds de la mine et ainsi préserver l’accès à cette zone, ce qui pourrait devenir difficile si la quantité de stériles utilisés pour la structure des descenderies augmente et s’ils occupent une trop grande partie du fond de la fosse. En outre, au vu des exigences de plus en plus strictes en matière de réglementation et de déclaration des émissions, un équipement plus volumineux ne sera pas nécessairement synonyme d’une réduction des émissions par tonne déplacée. Cette étude analyse l’incidence de la taille des camions de transport sur des aspects actuellement non intégrés dans l’aménagement classique des mines, notamment la création de routes permettant le passage d’un équipement plus volumineux, la variation de l’épaisseur de la couche d’asphalte des routes en fonction de la taille des camions de transport, ainsi que la consommation de carburant et les émissions. Les résultats indiquent que ces relations ont des répercussions importantes sur les coûts. Ainsi, on recommande d’accorder une attention accrue aux capacités d’augmentation de la taille de l’équipement dans l’aménagement des mines. ¦ MOTS CLÉS aménagement des mines, camion de transport, charge utile, résistance au roulement, résistance due aux rampes, résistance totale, route de transport, sélection du materielINTRODUCTION Over the past five decades, the mining industry has progressively attempted to increase production rates through the use of larger haulage equipment. Each new generation of mine is designed to operate with the most recent and often bigger equipment iteration, while older mines are re-evaluated to keep pace with upgraded mixed fleets. Whereas production gains are often realized with larger equipment, there are additional aspects to consider when evaluating the feasibility of mo"

Jan 1, 2019

By CIM Mineral Resource

On January 9, 2018, the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Council formed the CIM Mineral Resources and Mineral Reserves Committee (CIM MRMR Committee), which is a combination of the previous Standing Committee on Reserve Definitions and the Best Practices Committee. As part of its mandate, the CIM MRMR Committee updates guidelines for use by Industry, which include the Uranium Practice Guidelines. The 2024 CIM Uranium Leading Practice Guidelines were adopted by CIM Council on November 22, 2024, and supersedes the 2003 version. The main principles and guidelines relating to preparation of Mineral Resource and Mineral Reserve (MRMR) estimates are provided in the CIM Estimation of Mineral Resources and Mineral Reserves Best Practices Guidelines (MRMR BP Guidelines, as updated from time to time). The MRMR BP Guidelines provide information pertaining to metalliferous and other deposits and many sections are readily applicable to the preparation of MRMR estimates for uranium deposits. However, additional guidance is appropriate for uranium deposits due to the radioactive nature of uranium, and its amenability, in some cases, to in situ recovery (ISR) mining methods.

Nov 1, 2024

By K. Cybulski

Coal dust explosions still remain the main hazard in the coal mining sector, notwithstanding their relatively wide recognition compared to other hazards and the development of effective methods of prevention. Coal dust explosions are still the cause of numerous catastrophes, often leading to fatalities. Fortunately, they rarely occur, and it is for this reason that their hazardous impact is often underestimated. This problem in Poland is being exclusively solved by the Central Mining Institute, Experimental Mine Barbara. Here, basic research on the phenomenon of coal dust explosions and prevention methods is carried out, as well as investigations into the causes and circumstances of past accidents. After 15 years of no coal dust explosion accidents in Poland (1987?2002), a few coal dust explosions have recently occurred, with tragic consequences. These events have taken place not only in hard coal mines, where the presence of dangerous coal dust is the result of common production cycle, and safety measures against coal dust explosions are subject to specific regulations, but also in coal-fired power plants. This is of special concern because prior to 1987, such accidents had been been reported only for coal mines and not for coal-fired power plants. In recent years, two dust explosions occurred in Polish power facilities: the Dolna Odra and Turow power plants. In both cases, coal dust explosions occurred in the fuel supply system, but biomass dust was also involved. The explosions caused significant damage to the systems and buildings. This paper gives description and schematics of the regions of catastrophic coal dust explosions that have occurred in recent years in Poland, as well as the results of post-accident investigations, presenting the coal dust explosion hazard at the accident scene The results specify in detail the state of safety measures against coal dust explosions in light of the relevant regulations in force, including amount of deposited coal dust, content of incombustible matter in coal dust, free moisture content in coal dust, state of coal dust explosion safety zones, and state of explosion barriers. The conclusions from the site inspection and post-accident investigations presented enable us to determine locations of explosion initiation, probable ignition sources, range of explosion flames, and explosion barrier performance. A complete elimination of coal dust explosion hazard at the site of dust deposition is practically impossible to achieve. Similarly, a total elimination of ignition source, which may be related to the occurrence of other natural hazards, equipment malfunction or human errors, is impossible. The examples of tragic events that took place in Polish coal mines and coal-fired power plants highlight shortcomings and mistakes made in terms of assessment and prevention measures taken against the coal dust explosion hazard.

Aug 1, 2013

By K. J. K. Weglo, M. U. Savich

"At the Falconbridge Limited, Canadian Nickel Division, Sudbury Operations, we investigated the ""NO NOISE"" ear muffs model NN3-F which is a Swedish product with foam-filled sealing rings (the Hellberg Standard Volume Hearing Protector). It is used extensively at Falconbridge mines in Sudbury.The research which was carried out in the four Falconbridge mines was conducted under three different headings: manufacturer&apos;s attenuation data (psychophysical method), clamping force and head size (bizygomatic diameter), and attenuation tests (physical methods) under working conditions.Manufacturers of hearing protectors claim their products offer noise reductions of 23 decibels (NRR) or more, but they fail to point out that this reduction is obtainable only under ideal conditions. The reality of attenuation under working conditions, as several studies have found, is quite different.Methods for using short measurements to determine the noise exposure index, and for controlling muff-wearing habits, were developed at the Elliot Lake Laboratory. Measurements taken at Falconbridge on ""NO NOISE"" ear muffs revealed that they have a practical attenuation of some IO to 13 decibels. It is important to note here that measurements also revealed that clamping force (thus attenuation) was in an inverse relationship with ear muff comfort. Measuring attenuation using noise dosimeters was a difficult job. Not a single surveyor would accept these measurements (physical method) for absolute accuracy. Apart from that, it was impossible to measure, in one shift, more than two work stations. Because of this, we sought a solution: measuring head size and clamping force in relation to actual attenuations.A detailed analysis of the relationship between attenuation and head size/clamping force was done at four mines. Standard deviation ellipses (standard error ellipses) for head size versus clamping force are in close agreement with measurements that were carried out. In order to measure clamping force an apparatus was constructed and a method for measuring suspension system durability is described in Appendices Band C of this report. At the same time we sought to reduce deterioration of ear muffs in mines as well as to put in place a system whereby attenuation can be controlled and improved. The clamping force apparatus can be operated automatically. The proposed control system is quick, simple and efficient . This system is equally applicable in small and large mining operations, and it can be totally automated and the data computerized for audit of the results. This control system is a new step in controlling ear muff attenuation in working environments.From these measurements of NN3-F ""NO NOISE"" muffs it can be concluded that ear muffs are not the total solution to protect the worker from noise.As the results were evaluated folio wing measurement, Falconbridge switched from the NN3-F ""NO NOISE"" muffs to approximately 90% Mark V ""NO NOISE"" muffs and 10% Mark V MSA muffs. These new muffs showed much better head size versus clamping force relationship and can be expected to produce 14 dBA or better attenuation of noise. RESUMEUne étude des casques antibruit ""NO NOISE"" modèle NN3-F, de fabrication suédoise, avec anneaux d&apos;étanchéité en mousse (dispositif de protection contre le bruit ""Hellberg "" pour volume ordinaire)a été effectuée Ii la Falconbridge Ltd. , Division canadienne du nickel aux installations de Sudbury . Ces casques sont largement utilisés dans les mines de la Falconbridge Ii Sudbury.Cette étude aeu lieuen milieu de travail dans les quatre mines de la Falconbridge sous trois rubriques différentes soit: les données d&apos;atténuation du bruit du fabricant (méthode psychophysique), la force de serrage et la taille de la tète (diamètre bizygomatique), et les essais d’atténuation de bruit (méthodes physiques). Les fabricants de dispositifs de protection contre le bruit prétendent que leurs produits offrent une réduction du bruit s&apos;élevant Ii"

Jan 1, 1986

By Z. B. Karshigina, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva

At the present time of depletion of reserves of high grade rare earth deposits, it has become necessary to involve low grade raw materials in the production. Among the rare-earth deposits in Kazakhstan, the most advanced one is Kundybai. The mineralogical composition of ore is represented by the minerals: a-quartz SiO2, kaolinite Al2(Si2O5)(OH)4, muscovite KAl2(AlSi3)O10(OH, F)2, albite Na(AlSi3O8), rutile TiO2, and hematite Fe2O3. It contains: 59.1–68.5% SiO2, 19.1–28.4% Al2O3, 7.2–10.3% Fe2O3, 0.51–0.84% TiO2, 0.10–2.32% CaO, 0.39–2.10% MgO, and some other elements. Rare earths are located in the clay part (kaolinite, goethite) in the ion-adsorbing form, and they are represented by the main ore mineral churchite - YPO4·2H2O. In the ore the amount of rare-earth elements (total REEs) varies from 210 to 600 ppm. Elements of the cerium group predominate (La, Nd, Ce, Sm, Pr) and the yttrium group is represented by Y, Gd and Dy. Extremely thin intergrowth and accumulation of REEs in clay minerals cause difficulties in their recovery using flotation and gravitation beneficiating methods. The purpose of this work is the development of an extraction method for the main mineral components of ore with transfer of the total REEs into the solution with high extractive efficiency. Results of the experimental work into high-temperature processing (hereinafter referred to as sulphatization) of ore by sulphuric acid with subsequent dual-mode water leaching of the sulphate product (sinter) are presented in this manuscript. The influence on the ore sulphatization process of some physical and chemical parameters: liquid-to-solid (L/S) ratio (0.36–0.86 cm3/g), temperature (100 – 500°?), concentration of sulphuric acid (3.0–18.62 mol/L) and duration (0.5–2.5 h) was studied. Optimal technological parameters of the process were determined to be: L/S ratio 0.36–0.46 cm3/g; temperature 500°?; concentration of H2SO4 9.0 mol/L; soaking time 1.5 h. Under these conditions it is possible to obtain extractions of ~ 85% REE, as well as 58% aluminium and 10% iron. XRD and IR-spectroscopy analyses were used to determine the material constitution of sulphated cakes obtained under optimal conditions. It was found that the primary minerals are quartz and muscovite; however different sodium aluminium silicates and albite minerals are present as well. In the future, it is proposed that the leach residue cakes are processed into precipitated silica (“white soot”).

Jan 1, 2016