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Electrolytic Precipitation of Gold
Table of ContentsWeak SolutionStrong SolutionRegeneration of Cyanide in Electrolytic Precipitation This was introduced on a commercial scale as an adjunct to the cyanide process on the Rand for precipitating the weak and low-grade solutions resulting from the treatment of slime by decantation, and was known as the Siemens Halske process. The anodes were of sheet iron enclosed in burlap to
How Arsenic, Antimony Silver Compounds Affects Leaching
Ores containing silver in Arsenic and Antimony combinations offer considerable difficulties in cyanidation and it has usually been considered that the removal of these compounds by concentration was the only way to deal with them. G. H. Clevenger, however, when working on the ores of the Nipissing Mining Company of Ontario, Canada, found that by grinding exceedingly fine and treating
Sulphide concentrate leaching
Table of ContentsCyanide consumptionCyanidation of Flotation Concentrate The question as to whether concentration shall be included in the treatment of a given ore will often depend on the possibility or otherwise of recovering the precious metals from the concentrate at the mine. It may be suggested that if the concentrate can be cyanided after being separated from the gangue, why can
Effect of Manganese on Silver Leaching
In Mexico and elsewhere there are large bodies of valuable silver ore containing manganese which present great, and hitherto insuperable, obstacles to a satisfactory extraction by cyanide. The proportion of the silver that is soluble in cyanide varies greatly and may be as low as 5% only. The mere presence of manganese in the ore is not invariably accompanied by
How Arsenic Affects Cyanidation Leaching of Gold
The Influence of Arsenic in the Cyanidation of Gold Ores is explained by W. B. Blyth has he is of the opinion that the presence of arsenic in an ore does not necessarily cause that ore to be refractory to cyanide treatment. He thinks the idea arose from the fact that arsenic is so often accompanied by antimony, pyrrhotite or graphite, stating
Metallurgy for Recovering Gold from Telluride Ore
Table of ContentsRoastingTreating Raw with Bromocyanide Gold ore associated with Telluride is hardly soluble in ordinary cyanide solutions and special treatment is necessary for its extraction. There are two methods in use in such cases. Roasting The ore is ground dry to about 30 mesh and roasted; it is then ground to a slime in water or cyanide solution, usually in
Discrepancy Between Actual and Expected Recovery: Gold Metallurgy Accounting
Table of ContentsPlant Tonnage MeasurementTonnage of Pulp, as Ascertained by Density DeterminationPossible Met Accounting Error Due to Density of SolutionMoisture Determination Preferred in Certain CasesSampling Mill Feed Head and Plant TailingsHow to Sample Mill Feed HeadsHow to Sample Plant Tailings ResiduesSampling Pulp at Different Stages of the Gold Leaching CircuitDiscrepancy in Assay of Leach Circuit Tailings Everyone connected with cyanide plants
Continuous Gold Leaching and Tanks Short-Circuiting
Table of ContentsLoss in Extraction Due to Continuous SystemSlime Treatment by Leaching in Filter PressesWashing out Gold bearing Solution after the LeachingIncreasing the Dissolving Effect by a Succession of WashesImportance of Cyanide Strength in CyanidationEffect of Pulp Dilution on CyanidationTime of Agitation The system of continuous treatment consists in allowing the stream of pulp to flow continuously through a connecting series of agitator tanks, as
Calculating Gold Losses in Continuous Countercurrent Decantation
Table of ContentsCalculations for Dissolved Gold Value LossCalculation for Mechanical Gold Loss of Cyanide This is an interesting development of the old decantation process, and while it contains the same principle, of displacement by successive dilutions, the action is much more rapid, the same result is attained by the use of considerably less barren solution and it is continuous in
Pulp and Slurry Thickening Test and Calculations
Table of ContentsCoagulation of the Slime for SettlementRole of Electrolytes in Cyanide LeachingEffect of Lime Addition on Thickener Settling Rate The slime pulp or slurry on leaving the sand classifier with its proper admixture of lime is first led to some form of thickening device if, as is usually the case, the ratio of liquid to solid is too large for
Leaching Fine Gold
Many definitions of the word “slime” have been attempted to Leaching Fine Gold but the one that best expresses its meaning from a practical point of view is that given by Park that it is that part of the pulverized ore that is not percolable on a commercial scale without the use of pressure. The consequences of this definition are
Leaching Gold from Finely Crushed Ore (Sand Leach)
Table of ContentsSeparation of Sand and SlimeHamilton Collecting TankDouble TreatmentCaldecott’s Choke-discharge ConeHow to Leach GoldRetained MoistureDraining and Washing When the cyanide process was first introduced its application was confined to leaching, that is, treatment by percolation. By this method only such material could be worked as was sufficiently granular in texture to allow the necessary amount of solution to percolate
Free Cyanide vs Total Cyanide Determination
Table of ContentsCyanide Titration with Silver NitrateFree Cyanide DeterminationDetermination of Free Cyanide Method No. 1Free Cyanide Determination Method No. 2Analytical Determination Method of Free Cyanide No. 3Total Cyanide DeterminationHydrocyanic Acid DeterminationEstimation of Other cyanide Compounds It is obviously of the highest importance in controlling the action of a solution to find out what strength of cyanide and alkali it contains
Method to Measure Lime Content in Cyanide Leach Solution
Table of ContentsClennell’s Method for Protective AlkaliGreen’s Method for Protective AlkaliHow to Measure the Available Alkalinity of Lime This term is usually defined as “the alkaline hydrates and half the monocarbonates” whose action is to protect the cyanide from decomposition, by acids developed in the ore and by atmospheric carbon dioxide. Either oxalic acid or a mineral acid may be used
Assay Method of Zinc in Cyanide Leach Solution
To ascertain the presence of zinc add a few drops of sodium sulphide solution to 50 cc of the solution to be tested (which should be strongly alkaline), and heat to boiling point. If zinc is present it will come down as a flocculent white precipitate. It sometimes happens that a cyanide solution will contain an appreciable quantity of alumina,
Measure Copper Content of Cyanide Leach Solution
Table of ContentsThe Cyanide Measurement Method for CopperColorimetric Estimation of CopperMethod of Procedure To assay for copper contained in a cyanide solution, the first essential step of the method is to completely decompose all the cyanogen compounds. For this purpose Clennell recommends evaporating 100 cc of the solution to be tested with 5 cc of nitric and 10 cc of
Thiocyanide Thiocyanate Sulphocyanate Assay Determination
Table of ContentsSulphocyanate/Thiocyanide/Thiocyanate Assay ProcedurePotassium Sulphocyanate Method for Estimating the IronReduction Method for Estimating the IronFerrocyanide Determination Method The method usually given for detection of Sulphocyanate (Thiocyanide, Thiocyanate) is to acidify and add a ferric salt, a blood-red color indicating the presence of KCNS. Silver and copper, however, interfere, and if present in sufficient amount may entirely prevent the formation
Cyanate Determination Method
Clennell gives among other cyanate assay methods the following based on the fact that when KCNO is treated with an acid it does not decompose into HCN but reacts in the sense of the equation, KCNO + 2HCl + H2O = KCl + NH4Cl + CO2 By determining the amount of ammonium compound formed a measure of the cyanate originally present
Determination of Ammonia and Ammonium Salts
Table of ContentsEstimation of Formates in Leach SolutionProcedure for Ammonia and Ammonium Salts Analysis The following method is given by Clennell to determine the Ammonia and Ammonium Salts content by assaying cyanide leach solutions. “Add excess of AgNO3, i.e., sufficient to precipitate all cyanogen compounds, then a little NaCl to remove excess of AgNO3, filter, wash, evaporate filtrate on a water bath to
Volhard’s Silver Determination & Argentometry
Table of ContentsFerric IndicatorDecinormal Ammonium or Potassium SulphocyanateMethod of Argentometry Procedure Volhard’s method is a type of Argentometric titration of silver content determination. The Volhard Method requires: a decinormal ammonium or potassium sulphocyanate solution, a decinormal silver nitrate solution, ferric indicator. A decinormal silver nitrate solution contains 16.988 grams of AgNO3 per litre, or 10.788 grams of Ag. It may be made up
Determination of Acetates
Julian and Smart state that cyanide solutions undergoing decomposition form not only formates but acetates. Clennell states that he has never found acetates present in a working cyanide solution unless lead acetate was being used, but on the assumption that acetates may perhaps be formed in certain circumstances he suggests the following equation. 4KCN + 5H2O = CH3CO2K + 2KCNO +
Determination Method to Assay for Soluble Sulphides in Leach Solution
This is seldom called for, but it happens occasionally that an appreciable amount of sulphide is developed in the cyanidation of concentrate, and some sulphide is sometimes apparent in the press effluent from aluminium precipitation which it may be desirable to estimate. For such small amounts Clennell recommends the colorimetric method. For this purpose a weak standard solution of sodium
Determine Oxygen Content in Leach Solution
Here is a way how to determine the oxygen content during gold leaching and Estimation of available Oxygen Content in Cyanide Solutions. Until recently no simple and reliable method has been known for the estimation of free oxygen in working cyanide solutions so that the one here described supplies something that has long been needed. The matter takes on an added importance