Blogs
Semi-Autogenous Grinding of Copper Ores
Table of ContentsMechanism of Size ReductionProcess Design FactorsPilot Testing of Projected SAG Circuits Mechanism of Size Reduction The spectrum of comminution mechanisms in a mill range from shattering of the rock by imposition of a load to abrasion by surface contact with other rocks. Since SAG represents a combination of autogenous and ball milling, a better understanding of the mechanism
Partially Saturated Zone Beneath Tailings Impoundments Seepage
Table of ContentsSummary of Methods of AnalysisData Requirements and Estimation ProceduresExample Calculations Conventional analyses of seepage through saturated media do not apply when tailings impoundments are located above a partially saturated zone. Three stages of seepage are identified and methods for estimating the seepage rates and duration of each stage, based upon flow in partially saturated and saturated porous media,
Determining Air Requirements for Reverse Air Lift
Numerous large scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid
Predicting Flotation Recovery
Unfortunately, many milling engineers rely rather heavily on percent recovery as a strict measure of a concentrator’s relative performance. The fallacy of this reasoning is not difficult to see since, by definition, percent recovery is a function of feed assay, tails, and concentrate grade. If copper tailing is constant, and it very nearly is for a strictly sulfide copper ore,
Factors having an Effect on the Power Consumption & Capacity of a Mill
Since man began beneficiating ores, a limited number of factors influenced the type of treatment. The ore itself has always been a factor. The first form of concentration was probably hand sorting, and the grade of concentrate and recovery had to be considered from the start. Five of the principal factors having an effect on the power consumption per unit
Phosphate Rock Beneficiation
Table of ContentsFlorida PhosphatesFort Green MineJordan PhosphatesBrazil PhosphatesNorth Carolina Phosphates Many new mines overseas have also become significant. This includes countries such as Senegal, Togo, Israel, Spanish Sahara, and Jordan. Limited production, often as by-products, has been noted in South Africa, Brazil, and other countries. In recent years, and even recent months, we have learned of many new areas being
Pellets for Direct Reduction
Table of ContentsProperties and Quality DemandsMetallurgical Test MethodsLKAB Pellets for Direct Reduction The iron ores mined by LKAB in the north of Sweden have excellent beneficiation properties. This gives LKAB a favourable position as regards the production of low silica pellets for direct, reduction. LKAB have concentrated on developing and marketing grades of pellets for the Midrex-Purofer-Hyl process group, i.e.
Overburden Stripping using Dredge and Draglines
Texasgulf’s Lee Creek Mine in Eastern North Carolina is using a combination Dredge-Dragline method for mining deep phosphate ore at a rate of 3.5 million tons per year. The matrix is thick, uniform in grade, and is processed into agricultural products. As in many other good mineral deposits, there are tough obstacles to overcome in recovering the ore. The dragline
Factors Influencing the Optimization of Autogenous Grinding Mills
Table of ContentsCapacity Variations and Feed SizeStudy of the Capacity/Size ProblemMode of Size Reduction The Stekenjokk plant employs a system with automatic support of the secondary mill with pebbles from the primary autogenous mill. As well as in the Aitik case the Stekenjokk plant has reached its rated capacity and performance after a short running in period. Capacity Variations and
Molybdenite Flotation Operating Variables
The number of variables which can effect flotation of molybdenite is very large. The analysis of flotation results indicate that molybdenite can be characterized into fast-floating and slow-floating components. The rates of fast-floating components, which do not create a problem in flotation, could be varied by changing agitation of airflow rates. Experimental For the laboratory flotation response experiments, a composite
Open Circuit Flotation
The use of open circuit flotation is common practice in porphyry copper ore concentrators and Australian copper concentrators and its use in other than copper concentrators is minimal a completely open flotation circuit is not used and it is general practice to have recirculation within the cleaner flotation stage. The Kotalahti Concentrator. The recovered minerals are pentlandite, chalcopyrite and pyrrhotite which
Nitric Sulfuric Leach of Copper Concentrate
Table of ContentsNitric Acid ProcessesProcess DescriptionLaboratory WorkProcess ParametersNitric Sulfuric Leach Process ImprovementsNO2 Leach ProcessExperimental ProgramNO2 LeachingElectrowinning Copper is leached in a staged reactor system utilizing nitric and sulfuric acids at 105°C. Iron is removed from the pregnant liquor as a jarosite and cathode copper is electrowon directly from the purified pregnant liquor. The spent electrolyte is recycled. Nitrogen oxides evolved
Mining Project Financing
Table of ContentsDefinition of Project FinancingAdvantages of Project FinancingSupport For Project FinancingProduction Payment Financing In the recent past, there have been numerous projections of the capital requirements for additional mine and processing capacities required to meet projected non-Communist World demand for minerals during the next 15 years. A consensus judgment would place this currently at $14 billion per year, with
How to Measure the Impact Forces in Ball Mills
Table of ContentsImpact Test BallInstrumented Ball TestsFactors Affecting Impact in Grinding Balls Of many physical parameters critical to design of grinding processes, impact of grinding media is among the most difficult to measure or predict. Yet impact of falling grinding balls, pebbles, or rods accomplishes the fine grinding essential to metallurgical recovery of most important minerals. Unfortunately, the same impacts
Liquid Ion Exchange Fractionation of Metal Ions
Table of ContentsDistillationMetal Ion FractionationFlow Sheets There are two basic problems when one attempts to separate a solution of metal ions utilizing a chelation-solvent extraction cascade (commonly called liquid ion exchange). First, it is impossible to produce any great degree of separation unless the separation factor (also called selectivity, which is the ratio of the distribution coefficients) is very large.
Process Plant Design
Table of ContentsMill SitingIntermediate StorageRadial Plants The radial system simplifies and improves control and supervision to a very considerable extent and can lead to a form of continuous plant operation with the separate sectors shutting down in succession for necessary maintenance while maintaining the overall plant operation. Radial Layout for Increased Treatment-Plant Productivity A great deal of time and trouble
Launder Design Procedure
The design of slurry launders has usually been based on strictly empirical concepts. An examination of the most common procedures reveals that they do not account for many of the variables that are recognized as significant for slurry transport. These may include flow rate, volume concentration of solids, solids specific gravity, solids size distribution, particle shape, launder geometry, and roughness
Lamella Thickeners
Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes designated Lamella Thickener, is a shallow depth sedimentation device which has been applied in
In-Situ Leaching Simulation – Uranium Ores
Table of ContentsThe In-Situ Simulation SystemThe Simulation Test MethodSimulation Test ResultsDiscussion of the Simulation Test Findings A laboratory method for the simulation of in-situ leaching of uranium was developed under contract to the Interior Department’s Bureau of Mines. Simulation tests using sulfuric acid, ammonium bicarbonate and sodium carbonate as reagents, and hydrogen peroxide as oxidant were carried out with representative
In-Situ Leaching & Borehole Mining
Table of ContentsIn Situ Leaching CopperShallow DepositsBlast Design—Fragmentation Research at Duval’s Sierrita MineLeaching Experiments at El Paso’s Emerald Isle MineContainment of Leach Solutions at Cyprus Mines Corporation’s Johnson MineMathematical ModelingDeep DepositsSite Characterization and Fragmentation Assessment at Homestake’s Seneca No. 2 MineIn Situ Leaching, UraniumWell Completion MethodsOptimum Well Completion Using Conventional TechniquesHydraulic Jet Technology for Perforating and Stimulating In Situ Uranium
Copper Lead Separation with Activated Carbon
Table of ContentsAdsorption of Amyl Xanthate on Activated CarbonAction of Activated Carbon on Chalcopyrite and Galena In many multiple-sulphide ore flotation processes, it is desirable to concentrate each of the various valuable minerals into separate products. Although there are a variety of techniques and chemicals which can be employed to produce efficient separation, two basic types of flotation circuits are
Dump Leaching Hydrology
Table of ContentsHydrology of Dump LeachingDump Flow Factors Affecting RecoveryDump Failures Resulting from Flow ProblemsHydrology of In-Situ Solution MiningRecovery Flow Patterns Dump leaching and in-situ solution mining have received considerable attention during the past few years due to their apparent economic viability and minimal environmental impact. Solution mining actually dates back to the 17th century when leaching of copper ore
High Gradient Magnetic Separator
Table of ContentsBasic Principles of Magnetic CaptureMethodology of Evaluating Separation PerformanceModel Applications High-intensity wet magnetic separators have been successfully introduced into, the mineral processing field over the past ten to fifteen years, due largely to rapid advancements in magnet design. Wet magnetic separation, until recent years, was applied solely to the concentration of minerals of high magnetic susceptibility, such as
High Capacity Thickener
Conventional practice is to add flocculant as a dilute solution to the feed slurry in a launder or feed pipe, possibly using staged addition so as to improve the floc growth. Mixing in launders is not necessarily optimum, and with deep launder pulp depths lower layers of slurry do not readily rise to the surface and become contacted with reagent.