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DryWashers Gold Mining
Table of ContentsDRYWASHER OPERATIONSmall Mechanical Gold WashersDry Washing GoldDRY WASHING In arid districts where water is scarce or expensive and a “dry” plant is proposed for the recovery of placer gold, a small dry washer may be the logical choice for processing samples. A number of small, hand-powered machines are on the market and most work quite well within certain
Fire Assaying; a Miniature Smelting Process
Fire assaying, in essence, is a miniature or small scale smelting process which recovers and reports the total gold content of the assay sample, including gold combined with other elements or locked in the ore particles. Because of this, a assay may report values that cannot be recovered by placer methods and it cannot be too strongly stressed that when
Gold Nugget Effect Definition in Sampling
In typical gold deposit (with gravity gold) the variations are so great and the values are so low, any attempt to divide a sample by taking alternate shovels, mechanical splitting, or by other means will invariably yield erratic results. Rather than set out supporting theory which at best would be academic, two examples are offered to show what actually happens. One is
Gold Panning Technique
Table of ContentsHow to Prepare for PanningSuspension and StratificationWashing the PanCleaning the Gold PanInspect the Pan and Estimate Gold RecoveredRemoving Gold from the PanTips & Tricks on How to Improve Gold Panning TechniquePanning for Gold with a New PanPan factorRecommended pan sizeUse of perforated panUse of safety panPanning large samplesStage panningSupplemental dataUse as a geologic toolGold PanPanning for Gold Panning for gold
Marcy Scale
Determine the solid content of a mixture a fix volume of slurry is poured into the sample container, this sample volume is fixed because the container is filled until the slurry is even with or over flows through the opening on its side. The container is then hang on the scale and the weight of the mixture can then be
Gold Refining Process by Aqua Regia
The Gold Refining Process by Aqua Regia was introduced at the Pretoria Mint after the Miller process had been tried and abandoned owing to the alleged difficulty of treating the gold bullion extracted by the cyanide process. In the aqua regia process the gold is dissolved and precipitated. It is made very difficult if the silver exceeds 100 parts per
Purification of Gold by Electrolysis
The Moebius Process of Purification of Gold by Electrolysis is now in successful operation and is said to be specially suitable for refining copper bullion containing large proportions of silver and gold with small quantities of lead, platinum, and other metals, but is chiefly used in parting dore silver containing not more than 20 per 1,000 of base metals. The apparatus
Gold Refining Machine
The guard pot, with the clay pot in it containing 2 or 3 ozs. of fused borax, is placed in the furnace, and is heated gradually until the bottom of the clay pot is dull red. The ingots (of which the larger are slipper-shaped) to be refined, amounting in all to 650 to 720 ozs. in weight, are then placed
Gold Refining Crucibles
The guard pot placed for safety under the white pot and afterwards used for remelting the refined gold, is a plumbago crucible 8 ¼ inches high, 6 inches inside diameter, 5/8 of an inch thick at the top, and ¾ of an inch at the bottom, which is flat inside and stands on a cylindrical firebrick 5 inches in diameter and
Miller Chlorine Process
Table of ContentsThe Chlorine ProcessGold Refining FurnacePreliminary RefiningThe Miller Process at the Sydney Mint The use of chlorine gas for the purification of molten gold was first proposed by L. Thompson, and the results of his investigations were published in the Journal of the Society of Arts two years later. He stated that “ it has long been known to
Gutzkow Process to Refine Gold
This Gutzkow Process of parting by sulphuric acid was invented and patented by Mr. F. Gutzkow. It has been extensively worked in Germany and in San Francisco, and up to the year 1891 had been instrumental, on the authority of Mr. Gutzkow, in refining one hundred million dollars’ worth of silver. It is fully described in Percy’s Metallurgy of Silver and
Sulphuric Acid Parting of Gold & Silver
Table of ContentsGold Mixing and GranulatingSolution of the SilverWashing and Melting the Gold ResiduePrecipitation of the SilverCrystallisation of the Sulphate of Copper This process has now, in the majority of refineries, superseded the nitric acid method, which is much more expensive, owing to the higher cost of the acid used and of the plant required. The German chemist, Kunckel, who
Silver Chloride Reduction
The silver chloride is then reduced in lead-lined tanks by means of granulated zinc and water acidulated with sulphuric acid. Thirty-three pounds of commercial granulated zinc are stated to be enough to reduce 100 lbs. of silver from the chloride. The reactions involved are as follows: 2AgCl + Zn = ZnCl2 + 2Ag Zn + H2SO4 = ZnSO4 + H2
Gold Alloy Granulation
The gold to be parted must be approximately free from base metals, particularly from those which are not soluble in nitric acid, such as tin, arsenic, antimony. If these were present they would form insoluble oxides, which would remain with the gold, so that further refining operations would be necessary: they would, moreover, cause a great increase in the consumption
PARTING: Separate Gold and Silver by Melting
Table of ContentsCementationParting by Using Sulphide of AntimonyParting by Means of SulphurParting by Nitric AcidGranulation of the AlloysTreatment of the Gold ResidueTreatment of the Silver SolutionReduction of the Silver ChlorideParting by Sulphuric AcidCommon Parting Process Parting is the separation of silver from gold and a process during which the base metals are separated from both, but, as the presence of a
How Gold Bullion is Made
Table of ContentsWhat Elements does Gold Bullion ContainGold Melting FurnaceGold Refining MethodsCasting Gold Bullion IngotsSeparate Gold and Silver by Melting By whatever process gold may have been extracted from its ores, it is necessary to melt the crude bullion and cast it into bars so that its value may be ascertained, and that it may be put into a form convenient for
How to Make a Gold Bar by Casting Gold Bullion Ingot
Table of ContentsBullion Lost During Melting ProcessOsmiridium Gold Bar ContaminantHow to Make Gold Bars Yourself The operation of refining by one of the methods described above is necessary before gold can be exactly valued. When base metals other than copper are present, segregation occurs and the solidified metal is not uniform in composition. The result is that the exact value of the
Gold Refining Methods
Table of ContentsRefining Gold by VolatilisationRefining Gold by by OxidationUsing Air to Refine Gold by Oxidizing Gold BessemerisationOxidation by NitreOxidation by Metallic OxidesChlorinationGold Refining by Sulphurisation How to Use Iron and Carbon to Refine Gold The processes used for Gold Refining are as follows: Volatilisation. Oxidation (a) by air blowing or roasting. (b) by “ bessemerising” (c) by nitre. (d) by metallic oxides.
Gold Melting Furnaces: Key Features and Applications
Table of ContentsWhat Furnace is best to Melt GoldMelting Furnace CruciblesMelting Gold Bullion The furnace used for melting gold bullion is of simple construction. It may be round or square, with walls consisting of an outer layer of ordinary brick and an inner layer, at least 4 inches thick, of the best firebrick. There is often a complete outer casing
Mining Geology Sampling Methods: Channel, Chips, Core
Table of ContentsSampling Methods & TechniquesSample Gold and Sulphide MineralsFactors to Consider when SamplingGeology Sampling GuidelinesGeological ReconnaissanceHow to Choose a Sampling MethodHow Many Samples and What Size Samples to CollectHow to Insure Sample RepresentativitySurface SamplingSampling Hand-dug ExcavationsSampling Machine-dug shaftsSampling with a Backhoe ExcavatorsSampling Bulldozer TrenchSampling with Churn DrillsWhy use Caution when SamplingHow to Collect a Bulk SampleHow to get a Grab SampleDrift
Sample Salting in Geology
There are two kinds of sample salting: intentional and innocent. Intentional salting can be defined as the surreptitious addition of valuable material to a sample with intent to deceive. Innocent salting, which can have the same end effect, can be accidental or the result of carelessness or improper working procedures. Although intentional salting is seldom encountered, only the engineer who
Methods of Testing Cyanide Solutions
Table of ContentsEstimation of Gold and Metals in Cyanide SolutionsDetection and Estimation of Sulphides in Potassium CyanideEstimation of the Reducing Power of Cyanide SolutionsEstimation of Oxygen in Working Cyanide SolutionsEstimation of Bromo-cyanogenEffect of Thiocyanates on Metallic Gold The method given above is difficult to apply when solutions containing soluble cyanides of zinc and other metals require to be titrated. “
How pH Affects Cyanide Decomposition & Use Alkalinity to Preserve Cyanide
Since acidity of the ore causes decomposition of the cyanide, an obvious method of reducing the loss is to add alkali in some form. Before doing this, the free sulphuric acid and soluble salts may be removed by leaching with water, and then a solution of caustic soda or lime is run on to the ore, and after standing for
Potassium Cyanide Chemistry on Minerals & Metals
The ordinary gangue of most ores (silica and silicates of the alkalies and alkaline earths) exercises no direct influence on the cyanide solution. The carbonates of the alkaline earths are also probably without influence. The decomposing effects of sulphides of the heavy metals vary with the physical state of the sulphides. Metallurgists found that dilute cyanide solutions exercise a “ selective action