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Types of Dredges
Table of ContentsAccording to the Motive PowerTypes of DredgeDREDGE TYPES The type of a Dredge is defined according to the Nature of the Work they do. Under this heading bucket dredges may be classed as: River dredges; paddock dredges. The river dredge is designed to work with some depth of water underneath it, and is not called upon to cut its own
Electric Dredge
Small electric dredges are great where water power is available within reasonable distance, electricity may be generated and transmitted by cable to the dredge, proving an economical substitute for steam, especially in localities where fuel is dear. The small space, too, occupied by the plant, and the ease with which it is handled, make electricity a very convenient power for
Steam Dredge
The first steam dredge of the bucket type was launched on the Clutha in 1881. Such dredges differ from current-wheelers only in being provided with engine and boiler in place of the undershot wheel. The use of steam machinery, of course, increases the initial cost, adds to the working and maintenance expenses, and necessitates the employment of skilled mechanics. But
Current Wheel Dredge
In the Current-wheel Dredge, the mechanism on these dredges is driven by an under-shot water-wheel, placed at one or at both sides of the scow and rotated by the current. Such dredges work with most safety and regularity in about a 3-knot current. An instance of a machine of this kind is the Mannherikia dredge, working, in 1894, on the
Gold Dredge Components
Table of ContentsDredge HullDredge EngineDredge PumpsBucket LaddersThe BucketsDredge Grab Hooks Dredge Hull Among dredging hands, the “ hull ”—namely, “ port ” and “ starboard ” pontoons tied together—is usually termed the “ pontoon ” or “ pontoons.” The ordinary hull consists of two long, narrow pontoons, joined together for about a third of their length by a third small
Dipper Dredge
Table of ContentsSuction Pump DredgesThe Grabs or Clam Shell DredgeThe Bucket DredgeClassification of Bucket Dredges In its primitive form, the dipper dredge consists of a barge or pontoon, to the side of which is attached a long pole carrying a strong canvas or hide bag, or iron bucket, which is termed a ladle, spoon, scoop, or dipper, and which at
Zinc Electrowinning from Chloride Electrolyte
Table of ContentsElectrolysis CellElectrolyte and AdditivesTest ProcedureElectrolysis ConditionsDeposit ExaminationCurrent Efficiency and Energy RequirementStandard Electrolysis ConditionsEffect of HCl ConcentrationEffect of Zinc Concentration Chemical and electrochemical leaching processes using chloride solutions (FeCl3, HCl, CuCl2) and dry chlorination with Cl2 gas followed by leaching of the resultant chlorides are some of the methods considered for treating fine-grained Zn-Pb-Cu-Fe sulphide ores and concentrates. These
Laboratory Regrind Mill
A laboratory stirred ball mill was used in a batch manner, with the milling time being varied so as to produce a number of different product size distributions diameter ratio of one, and has a jacket through which cooling water is passed. The vessel is mounted on a turntable which is located on a thrust bearing. The turntable is restrained from rotating by an extension
Uranium Precipitation by Hydrogen Peroxide
Uranyl peroxide precipitation offers two advantages over other precipitation methods, product purity and product handling. However, since it is a less well known process than ammonia, caustic or Mag-Ox precipitation, it is helpful to demonstrate the advantages of hydrogen peroxide by comparing its performance with the widely known and used ammonia precipitation process. First, product purity is an obvious concern
Air Jig – Paddock’s Pneumatic Separator
The Paddock pneumatic ore separator is a jig, in which air is used instead of the fluid more commonly employed—water. Like the water jig, it consists of an inclined sieve, over which the crushed ore is passed, and through which the air is blown into the ore. The air current is intermittent, and being proportioned in strength to the thickness
Dredging Method
I desire to call the attention of the Institute to a novel system of dredging, which, it seems to me, may prove applicable, not only to river and harbor improvements, but also to certain varieties at least of alluvial and diluvial gold mining; that is, river-mining, bar-mining, coast-mining, and any other similar operations now carried on by means of coffer-dams
Solvent Extraction of Cobalt SX
Table of ContentsExperimental TechniquesExperimental ResultsSolvent CompositionExtractionWater-Ammonium Sulfate WashingpH-Controlled WashStrippingKineticsPhase SeparationContinuous Circuit OperationConclusions The United States produces essentially none of the cobalt and less than 10 pct of the primary nickel it consumes each year. However, it has been estimated that U.S. resources of cobalt and nickel are 842,000 and over 15 million short tons, respectively. Present yearly domestic consumption of
Scrap Silver Recovery
Table of ContentsDescription of Materials and EquipmentHoneycomb PanelsElectrolytic CellsPower SuppliesPreelectrolysis Preparation of Honeycomb PanelsShredding of Honeycomb PanelsSampling Honeycomb for AnalysisExperimental Procedures and ResultsSmall Rectangular CellLarge Cylindrical CellConclusionsRecommendations for Future WorkAppendix The Bureau of Mines undertook a study of recovery of precious metal values from surplus and obsolete electronic gear as a part of its continuing effort to achieve maximum use
SAG Semi-Autogenous Mill Steel Consumption
Does a SAG Mill reduce steel consumption? Do SAG mills cost less to operate compared to conventional rod or ball mill grinding circuits? Mining companies are always searching for new ways to cut costs. In order to be competitive and justify the tremendous capital costs of new projects, there has been a strong trend toward mills with a capacity of
Anemometer to Measure Flotation Cell Air Flow – Self Aspirating
Table of ContentsUsing the AnemometerMethod Factor RangeBuy an Anemometer I once used an Anemometer to Measure Flotation Cell Air Flow on Self Aspirating WEMCO machines. Overtime, operations & maintenance got lazy and never took care of cleaning the airflow supply pipe into the cell. It was clear flows were partially to completely blocked. I improvised the method and now found
Selective Flocculation and Flotation
Table of ContentsSample DescriptionPilot Plant ResearchFlowsheet, Equipment, and Test ConditionsMetallurgical ResultsWater ReclamationEstimated Reagent CostsSummary and Conclusions The Bureau of Mines undertook a research program to insure an adequate supply of iron raw materials for future iron and steel making needs. A sample was obtained of oxidized taconite from the western Mesabi Range in Minnesota, and the metallurgical response of the
Rod Mill Grinding
Table of ContentsLinear & Nonlinear Grinding ModelsExperimental MethodsBatch Mill ExperimentsContinuous Mill ExperimentsMaterial Breakage Kinetics in a Rod MillThe Linearized Batch Grinding ModelSimulation of Batch Rod Milling using the Linearized Grinding ModelMaterial Transport Through Rod MillsResidence Time Distribution AnalysisEffect of Operating Variables on Material Transport through Rod MillsSummary and Conclusions A detailed experimental study of breakage kinetics in a batch rod
Recycling Chrome Refractory Waste
Table of ContentsDescription of SamplesChemical AnalysesMineralogical AnalysesParticle Size DistributionBeneficiation StudiesRefractory EvaluationEnvironmental ConsiderationsSummary and Conclusions Chromite ore in combination with various quantities of magnesia is used in basic refractories. Refractories of this type are used as linings in steelmaking and copper smelting furnaces, rotary cement calciners, and glassmaking tanks. However, most of the consumption is by the copper and steel industry.
Ni-Hard Grinding Balls
Through a cooperative agreement, the Carondolet Foundry Co. of St. Louis, Mo., supplied 1,000 pounds of 2-inch Ni-hard balls for comparison with balls of other composition. Ni-hard balls are said to contain 2.5 to 6 percent nickel and 0.5 to 1.5 percent chromium. They have a Brinell hardness of 548. The company also furnished a stock of annealed, cast-iron balls.
Grinding with Pebbles VS Steel Balls
Operators in the metallics industry, sometimes forget that pebble mills are an important factor in fine grinding. However, pebble mills are not extinct, as is shown by reference to a recent paper on ore milling, wherein it was shown that five of the 44 so-called “ball” mills mentioned actually were pebble mills. If the nonmetallics industry included, pebble mills would
Why use Different Size Balls in a Mill
Table of ContentsOptimum Size of BallsTests with Different Mixtures of Balls in Conical, Cylindrical, and Grid MillsClosed-Circuit Grinding Several years ago, Davis assumed that the rate of wear of the different sizes of balls in a ball mill was directly proportional to the weight of each ball, and he evolved a formula for calculating a balanced charge. Operators have used
Impact of Ball Mills Diameter VS Length Compared Efficiency
Operators may rightly ask how much reliance should be placed on laboratory ball milling when they are using mills so much larger. This question was foremost in the earliest work at Rolla; in fact, in the beginning more attention was given to plant tests than to laboratory tests. The operators had calculated their results in terms of useful grinding and
Grinding Efficiency of Ball Chips VS new Balls Compared
Battered Reject Balls and New Spherical Balls Compared: Operators are sometimes at a loss to know when a mill should be dumped to discard the worn and battered balls. Similarly, the present authors found an unknown variable when they compared the laboratory work of a new grinding medium with the plant performance of media, some of which may have been