Gold Alloy Melting and Casting

Gold Alloy Melting and Casting

Table of ContentsMetals used in AlloyingGas and Electric MeltingDefects in IngotsSurface DefectsIngot ProportionsPorous IngotsDeoxidizersUse of Deoxidizers in Sterling SilverUse of Phosphorus in Gold AlloysCalcium Boride in Gold AlloysCasting TemperatureEffect of ImpuritiesSulfur in White Gold The problem of scrap is probably of greater importance in the production of gold, silver and other precious metal alloys than … Read more

Method for Estimating the Efficiency of Pulverizers

Table of ContentsImpact Grindability TestGrindability Test in Analysis of Mill PerformanceGeneral Discussion Grinding costs are an important item in cement manufacture, and the cost of power is one of the large items in grinding costs. Even where power is of secondary importance, cost items dependent on mill capacity are influenced by the efficiency with which … Read more

Screw Crusher

The Freeport Sulphur Co. built a portable crusher in 1944 that solved a problem that none of the crusher manufacturing companies contacted were able to do. Two of these crushers have now been in service for 6 years, giving satisfactory service in handling a million tons per year, and having a capacity of over 2000 … Read more

Hardness and Toughness of Rocks

The speed of drilling rock has become an important factor in mining operations, while the placement of holes, kind, and quantity of explosive used are equally important. These are a function of the rock hardness and toughness. Both of these factors must be considered in compiling a table that will enable a mine operator or … Read more


Table of ContentsConcasseurs PrimairesConcasseurs a MachoiresConcasseurs GiratoiresComparer Concasseurs PrimairesConcasseurs SecondairesConcasseurs a ConeTypes de Concasseurs de PierreCircuits de Concassage Le concassage constitue la premiere etape de la comminution. Son objectif n’est pas la liberation des mineraux, mais simplement la reduction de dimension afin de faciliter la manipulation ulterieure du minerai. II est normalement fait a sec … Read more

Use of Bleaching Clays in Water Purification

Table of ContentsAdvantages of Bleaching ClayUse of Clay at AtlantaConclusionAcknowledgments Bleaching clays have been used extensively in the oil-refining industries for a number of years. Their use in water purification is relatively recent and less extensive. They are frequently classified as (1) those naturally active and (2) those active after artificial activation with acid. Fuller’s … Read more

Ball Mill Grinding

Table of ContentsBall Rod and Pebble MillsBall LoadsScreens and FlakinessUnits of SurfaceBatch and Continuous Grinding ComparedBatch Ball Milling at Various Speeds and Ore ChargesBest Wet  and Dry Batch Ball MillingSelection of Volume of Ball Loads in Continuous Dry Open Circuit GrindingNonferrous Media and Steel Balls ComparedSillimanite BallsTetrahedrons and Spherical Balls ComparedBattered Reject Balls and New … Read more

How to Remove Quartz & Impurities from Refractory Clays

Table of ContentsPhysical and Chemical CharacterBeneficiationDetermination of Firing PropertiesLaboratory InvestigationsSandy Flint Clay A. P. G. 1Physical and Chemical CharacterBeneficiationWet-Table and Wet-Cyclone ConcentrationDetermination of Firing PropertiesSandy Flint Clay H.-W. 2 Physical and Chemical CharacterBeneficiationWet-Table and Wet-Cyclone ConcentrationDetermination of Firing PropertiesSandy Plastic Clay A, P. G. 3Physical and Chemical CharacterBeneficiationWet-Table and Wet-Cyclone ConcentrationDetermination of Firing PropertiesPyritic Plastic … Read more

Fine Grain Lead Zinc Sulfides Flotation

Table of ContentsThe OresPhysical CharacterChemical DescriptionLaboratory StudiesNabob OreHighland Surprise OrePend Oreille OreLiberal King OreSidney OreDouglas Ore This investigation has shown that lead and zinc sulfide minerals, in pulps containing particles all less than 9 microns in size, may be selectively recovered by froth flotation. All but one of the samples yielded lead concentrates-containing at least … Read more