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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
Increase Potassium Cyanide Leaching Reaction with Gold & Mercury
These methods are described here for convenience, as being more intelligible after the chemistry of the process has been discussed. The necessity of the presence of oxygen has already been dwelt on above. It has, however, been frequently pointed out that in the interior of a mass of ore undergoing treatment the conditions are not favourable for the maintenance of
Oxidised Pyrite Leaching by Potassium Cyanide
When the pyrites occur in tailings which have been subjected to the action of the weather for some time before treatment, compounds are formed which are more prejudicial to the solution than the sulphides. Sulphide of iron, FeS2, is oxidised by air and water, ferrous sulphate and free sulphuric acid being formed, thus: FeS2 + H2O + 70 = FeSO4
Zinc Box for Gold Bullion Precipitation
It was generally believed at one time that the precipitation of gold and silver by zinc was effected by simple displacement, according to the equation: 2KAuCy2 + Zn = K2ZnCy4 + 2Au Some considerations have been adduced, however, which throw doubt on this view. It is well known that a considerable excess of free cyanide must be present to enable the
Effect of Potassium Cyanide on Gold & Metals
The discovery that metallic gold is soluble in potassium cyanide came after studying the action of cyanides on plates of gold, and announced that they were slowly dissolved. Metallurgists pointed out that gold-leaf is dissolved by a dilute solution of the salt, and also showed that if the gold floats on the surface of the liquid, so that one side
Gold Vat Leaching
Table of ContentsLeaching Gold in VatGold Lixiviation in VatPreparing the Ore for Vat CyanidationReprecipitation of Gold & Silver in the Leaching VatsVat SumpsVat Tailings Disposal Gold Leaching done in round vats, constructed of wood, concrete, or iron and steel. If wood is used it is covered by a coating of paraffin paint, or by a mixture of asphaltum and coal-tar. Concrete and brick vats are
How to Prepare and Storage of Cyanide Solution
Table of ContentsStrength of the Leach SolutionTesting Cyanide Solutions Strenght The cyanide is usually dissolved in a little water before being added to the stock solution, as the amount of KCy present is more easily determined in a strong solution than in any other form. A special dissolving vat of small size is often provided and is placed at a
How to Make Gold Bullion
Table of ContentsDirect FusionRoasting followed by FusionAcid TreatmentThe method of cleaning-up as follows: Various gold bullion making methods have been suggested for effecting the elimination of the zinc and other base metals. The chief ones are: Direct fusion with fluxes. Roasting, followed by fusion. Treatment with sulphuric acid, followed by fusion. Lead fusion and cupellation (Tavener process). Volatilisation of the
Cleaning the Gold Precipitate Bullion Box
There is one precipitation house and refinery common to all the leaching buildings. The method of precipitation is by zinc shavings, which, with slight modifications, answers admirably for all strengths of solution, the strong solutions ranging from .70 per cent. KCy to .25 per cent. KCy; the weak from .25 per cent. KCy to .10 per cent. KCy, and the
Cyanide Solution Strength Test
The strength of the cyanide solutions is tested by silver nitrate, using 10 c.c. of the strong and weak solutions respectively (diluted to about 100 c.c. with water) and taking 100 c.c. of wash-water undiluted. In each case a few drops of a 5 per cent, solution of potassium iodide are added. When the titration is done very rapidly and
Chemical Precipitation on Mercury
The Chemical Precipitation on Mercury of the Gilmour – Young Process is a method that has been employed at the Santa Francisca Mine, Nicaragua. The ore contains a very large percentage of clay, the slimes amounting to 70 per cent, of the ore. The ore is crushed by a No. 5 Krupp ball mill through a 30-mesh sieve, and is charged
Electrical Precipitation on Mercury or Amalgamated Plates
In the Siemens-Halske Electrical Precipitation process, the gold is deposited from solution by the passage through the liquid of a current of electricity. Moreover, as the precipitation is as readily obtained in extremely dilute cyanide solutions as in those containing 0.1 per cent, or more, very weak solutions are used in dissolving the gold from the ores when electrical precipitation
Cyanide in the Stamp Battery
Use of Cyanide in the Stamp Battery to treat the ore direct from the stamp milling battery instead of first passing it over amalgamated plates. Ore can be crushed with cyanide solution instead of water, and led at once into the filtering tanks. The results are stated to have shown that the coarse gold resisted the attack of the cyanide for so
Treatment of tellurides without roasting
Table of ContentsTreatment of ConcentratesTreatment of Ore Slimes by Filter PressingTreatment of Sulpho-Telluride Ore Among other suggestions for rendering the presence of oxygen in cyanide solutions unnecessary, the most striking was The Sulman-Teed Process, who use cyanogen bromide, CNBr. The addition of this substance to a solution of potassium cyanide makes it much more rapid in dissolving gold. They put
Zinc Dust Precipitation
The Merrill System or method or Zinc Dust Precipitation was introduced in 1897 at Marysville, Montana; in the plant of the Montana Mining Co., and subsequently at the Homestake Mine in South Dakota, where 130,000 tons of ore are treated per month and 4000 tons of solution precipitated every 24 hours. With very few exceptions this process has been installed in all
Rock Crushers
This invention relates to jaw rock crushers. In such known crushers, eccentrics or unbalanced rotors drive one or two oppositely situated swing jaws. The disadvantage of the known jaw rock crushers in comparison with known gyratory crushers lies in their cyclical work. i.e. the jaw makes one power stroke and one idle stroke during one revolution of the eccentric shaft.
Gold Chlorination Process in VAT
Table of ContentsThe Munktell Chlorination ProcessThe Cassel-Hinman Bromine ProcessPermanganate Chlorination ProcessChlorination The Munktell Chlorination Process This method was devised by W. Munktell, who seems to have worked it out without having visited either the vat or the barrel chlorination works already established in other parts of the world. The process enjoys the distinction, according to the published accounts, of having
The Barrel Gold Chlorination Process
Table of ContentsWorking Principles of Barrel ChlorinationMechanical Difficulties of LeachingHow Gold Precipitates after ChlorinationFerrous SulphateSulphuretted HydrogenSulphurous AcidCharcoalCopper Sulphide and Iron SulphideElectrical PrecipitationHow Barrel Chlorination WorksBromination The use of revolving barrels for chlorinating ores was perhaps suggested by the old Freiberg method of barrel amalgamation. It has already been mentioned, p. 239, that Dr. Duflos used a revolving barrel in some of
Plattner Gold Chlorination Process
Table of ContentsPlattner Chlorination Process How to Use the Plattner Chlorination ProcessChlorination VatsHow to Load Ore in the VATSHow to Generate Chlorine GasOre Impregnation Time by Chlorine GasChemical Reactions in the Impregnation VatHow much Chlorine is required to leach goldLeaching the ChargePrecipitation of Gold in Chlorination ProcessUsing Liquid Chlorine The use of chlorine as an agent for the extraction of gold from ores was first
Which Grinding Mill is Best for Regrinding by Types
Ball Mills and stirred mills are applied across a wide range of applications, but for each ore there is optimum efficient range. The figure to the left shows the typical application ranges for ball mills and stirred mill. The Vertimill is always more efficient than a ball mill with energy savings ranging from 30% to greater than 50%. The transition
Laboratory Crushing Tests
The first step in minerals beneficiation of an ore is normally crushing which has been defined “as the operations required to reduce run-of-mine ore to grinding feed size”. It would therefore follow that the first metallurgical testing should be conducted on run-of-mine ore but, due to its size, this would be rather impractical. However, there is little need to test
Chain Mill
A Chain Mill is a total amateur’s tool for “crushing or grinding” rock. It is a set of chains attached directly at the end of a 1700+ RPM motor. The chain will beat your rock to bug-dust, pulverise it, and any gold it might contain, into a size fraction so fine you will not be about to recover it using
DIY Ball Mill Plans – Homemade Rod Mill Drawing
By this drawing, it is suggested that a typical homemade laboratory rod mill or ball mill might be fabricated from 20 cm (8 inches) diameter schedule-40 type 316 stainless steel pipe and would be about 38 cm (15 inches) long. The plans show stainless steel grinding rods for this size of mill may be a graduated charge from 25 to