Blogs
Grinding Circuit Modelling
Table of ContentsGrinding CircuitsSampling and sample preparationPrimary GrindingOverall performanceSecondary GrindingBreakageSimulationPrimary GrindingMaximum tonnageEffect of Grind on Flotation PerformancePrimary GrindingSecondary GrindingExperimentalBall Size DistributionCircuit PerformancesSimulation Grinding Circuits Fine grinding is carried out in five primary circuits, six secondary circuits and one regrind circuit which grinds copper scavenger concentrates and copper cleaner tailings. A diagram of the primary and secondary grinding circuits showing sample
Caisson Thickeners
To discuss “Large Diameter Thickeners in the Phosphate Industry” is to discuss large diameter slimes thickeners in general. Since 1948, Dorr-Oliver has supplied these machines to the phosphate industry, originally as a means to reduce pumping costs, but more recently for environmental reasons as well. With the exception of the Caisson thickener, all the types of thickeners to be discussed
Waste Dump Leaching Copper
Table of ContentsCopper Leaching FundamentalsExperimental ProcedureModel DevelopmentThe Continuity EquationIntrinsic Mineral Leaching KineticsChalcociteSecondary CovelliteNatural CovelliteChalcopyritePyriteComparison of the Leaching Rates of Copper MineralsApparent Ferric Ion ActivityLate Enhancement of the Leaching RateParticle-Size DistributionMathematical Leaching ModelVerification of the Leaching ModelComparison of Leaching Parameters for Different OresCopper Extraction and Ferric Ion Concentration ProfilesOres Containing a Variety of Copper Sulfide Minerals To help maintain an adequate
Insoluble Anodes for Electrowinning Zinc & Metals
Table of ContentsExperimental ProcedureMaterials and EquipmentOperation of the Electrolytic CellMeasuring PotentialsResults and DiscussionPolarization Behavior of Pb-Ag AnodesH2SO4 SolutionsNaF and KF SolutionsOvervoltage MeasurementsTestingSuperimposed Alternating Current on Direct CurrentMnO2-Coated AnodesPbO2-Coated Lead AnodesConclusions and Recommendations This Bureau of Mines investigation was prompted by the need for a stable anode for electrowinning metals, particularly zinc and copper, from acid solutions. The polarization behavior of Pb-Ag
Acid Leaching of Uranium
Acid leaching has been used in the uranium milling industry since the mid-forties and has accounted for a majority of the production since that time. It is preferred over carbonate leaching because of its greater efficiency in recovering uranium. Consequently much research has been done on the factors which influence the kinetics of the oxidation of uranium, as well as
Recycling of Stainless & Speciality Steel
Table of ContentsHow It WorksTest Results To reuse chromium, nickel, and molybdenum now lost in stainless and specialty steel-making wastes, and simultaneously to overcome the current environmental problem resulting from landfilling these wastes. A variety of stainless and specialty steelmaking wastes are agglomerated and recharged into the plant’s electric arc furnaces. How It Works Stainless and specialty steel-making wastes such as
Rationed Ball Mill Charging to Improve Grinding Efficiency
Table of ContentsBall SizesWeight Percent of Each SizeRecharge ScheduleProduction Test ProcedureResults Ball Sizes As mentioned earlier, years of operating experience indicated that the maximum ball size for the 2.93 m Climax mills was 76 mm. Application of Azzaroni’s equation confirmed that 76 mm was the correct maximum size. The selection of the second, smaller ball size was made by analyzing historical
HYL III Direct Reduction Process
Table of ContentsHYL III Process DescriptionReducing Gas GeneratorReduction Unit The objective of the operator of a direct reduction plant Is to optimize the cost of inputs required to obtain each tonne of DRI. Three major factors affecting the unit cost of the product are iron oxide feedstock, energy, and plant productivity. For the past decade, most direct reduction plants have
Hydrogen Chloride Crystallization of Aluminum Chloride Hexahydrate
Table of ContentsMaterials and EquipmentTest ProcedureCrystallizer Configuration and Gas Flow RatesAluminum Chloride Hexahydrate Yield as a Function of HCl ConcentrationEffects of Temperature on ACH Crystal PurityEffect of Aluminum Chloride Concentration on ACH Crystal PurityConclusions As part of its effort to produce cell-grade alumina from clay, the Bureau of Mines investigated the hydrogen chloride gas-sparging crystallization of aluminum chloride hexahydrate (ACH)
Dust Controlling Water Sprays
Table of ContentsBench-Scale TestingFull-Scale Model-Mine TestingConclusionsMachine Mounted Ventilation SystemResults and Conclusions High-pressure shrouded sprays were first tested on a bench to determine air-moving capability and dust collection efficiency. The bench-scale tests indicated that at 500 psi and above, the dust collection efficiency, when sampled downstream of a water eliminator, was about 99 pct for two types of nozzles. However, for
Heavy Media Media Recovery – Magnetite & Ferrosilicon
Table of ContentsMediaMedia RecoveryMedia Recovery Circuit Design Media Magnetite (Fe3O4) and Ferrosilicon (FeSi) are the most widely used media. Magnetite is used up to a specific gravity of 2.2; a mixture of FeSi and Fe3O4 is used for the range 2.2 to 2.9; above 2.9 FeSi is used alone. Using FeSi, separations up to specific gravity of 3.4 have been
Heap Leaching Gold & Silver Ores
Table of ContentsLaboratory Equipment and MaterialInvestigation of Process VariablesEffect of the Amount of Portland Cement added on Percolation Flow RateEffect of Portland Cement Addition on AgglomerationEffect of Curing Time on Percolation Flow RateEffect of Water Addition on Percolation Flow RateSummaryEffect of Wetting with Cyanide Solution on Leaching PeriodPilot Scale Testing of Agglomeration TechnologyGold OreSilver Mine Waste MaterialSilver Mill TailingPotential Benefits
Gold Heap Leaching Practices
Table of ContentsCrushing and Ore StackoutLeachingGold Recovery Heap leach gold recovery techniques are employed at Ortiz. Caustic cyanide solutions are sprayed onto crushed rock piles, dissolving the metallic gold from within the rocks and carrying it out as a ‘pregnant’ gold containing solution. The solution is then passed over carbon particles which the gold preferentially precipitates upon. The gold loaded
Copper Cementation System for Small Scale Mining Operations
Table of ContentsMaterials, Equipment, and ProceduresCopper Cementation with Automobile ScrapRotating Drum Operating VariablesOpen Versus Closed DrumPeripheral Versus Center DischargeDrum Rotating SpeedSolution Feed RateDrum Operating ConditionsStagewise CementationCopper Cementation with Shredded Automobile ScrapIron ConsumptionCement Copper PurityComparison with Shredded Tinplate-Gravity Launder ProceduresCost EvaluationRotating Drum for Copper Cementation using Automobile ScrapConclusions We studied the precipitation of copper from dilute acidic sulfate solutions using shredded
Sample Preparation for Gold & Silver Assay
Sample Preparation: Aqua regia with, occasionally, the addition of hydrofluoric acid is the most used lixiviant, and is applicable to most ore types. Other combinations of acids as well as cyanides are also used, and pre-roasting is sometimes applied. Digestion time and amount of reagent vary, quite naturally, with the amount of acid consuming materials in the sample. Thus, raw
Merrill Crowe vs Carbon
Several economic comparisons have been made between carbon systems and Merrill-Crowe systems. One of these, a systematic comparison completed by DeMent and King (1982) is summarized below. Five separate conventional mills involving both Merrill-Crowe and the CIP processes were compared from an economic viewpoint. The gold concentration on the feed leach liquor ranged from 0.428 to 0.054 oz of gold
Foam for Dust Control
Table of ContentsExperimental ProcedureFace DrillCrusherFace DrillCrusherDescription of Foam Generator The Code of Federal Regulations (Title 30, Chapter 1, Part 57, Section 57.5-1) requires that metal and nonmetal mines shall maintain a time weighted average (TWA) for total and respirable airborne dust concentrations below that established by the American Conference of Governmental Industrial Hygienists in 1973. This TWA for total dust
Carnallite & Sylvinite Ore – Potash Flotation
Table of ContentsExperimental MaterialsExperimental ProceduresTwo-Stage Mechanical DeslimingDecomposition-Leach of the Carnallite OreInsoluble Slimes FlotationPotash FlotationDirect Potash FlotationFinal Product LeachingExperimental Results and DiscussionMechanical DeslimingInsoluble Slimes FlotationDirect FlotationSummary The mission of the Bureau of Mines minerals research program is to help improve minerals processing technology so that the Nation’s mineral needs can be fulfilled in a manner that reduces waste and ensures that
Flotaire Flotation Cell
Table of ContentsFlotaire System The Flotaire Cell can be constructed in many configurations, but presently, we prefer a round tank that is 2 to 4 m in diameter with an overall depth of about 5 m. Simplicity of design, and operation, is a principle attraction of the Cell and can be best understood by reference to Figures 1A and 1B.
Kiln Temperature Controller Guide
You wonder how to enter the burn off program in our programmable kiln temperature controller, so today we’re going to show you an Example of exactly how to do that. With your kiln all set up and plugged in it will flash showing ambient temperature; STOP or HOLD. You will access the program setting to enter the parameters by pressing
Fire Resistance of Conveyor Belts
Table of ContentsExperimental Apparatus and ProceduresFlammability ApparatusTest ProcedureCalibration of IgnitorResults and DiscussionFlame SpreadRadiant Preheat FluxIgnitor Heat InputBelt Width and HeightAir VelocityBelt MaterialSmoke EmissionFire Resistance Ratings by New ApparatusComparison of Fire Resistance Ratings With Other Methods Conveyor belt fires can present a serious hazard in the confined environment of an underground coal mine. To minimize this hazard, Federal regulations were enacted
Elutriation Bowl: Falcon & Knelson
Table of ContentsElutriationTwo Stage ConcentrationInstallationsLaboratory WorkSelectivityLow SG ApplicationsMineral SandsFerrous metal Elutriation Another enhanced gravity device was patented in 1935 by A. N. MacNicol (Figure 4). It is also a truncated cone but ribs divide the length into a series of slots. A water jacket and connecting holes are used to inject water and elutriate a bed of material in each.
Uranium Acid Leaching
Table of ContentsMechanism of Thorium LeachingPrecipitate FormationBacterial ActivitySulphuric Acid Consumption Mechanism of Uranium Leaching: Uranium leaching with sulphuric acid is a complex process governed by chemical dissolution, and the oxidation of uranium. It is controlled by surface etching, diffusion, and mass transfer within the ore. The physical parameters are in turn controlled by the physical properties of ore, and the ore
Cyanide Leaching Platinum Catalytic Converter Chemistry
Table of ContentsPlatinum Leaching IN Laboratory Hydrolysis of CyanideCharacterization of PGM SpeciesLeaching Rate StudiesConclusions Previous research by the U.S. Bureau of Mines showed that autoclave cyanide leaching of used automobile exhaust catalysts for recovery of platinum group metals (PGM) was technically feasible. This work involves a more detailed investigation of the chemistry of the dissolution of PGM in cyanide solutions. The PGM