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Gold Bromides
Gold Protobromide, AuBr, is a yellowish-green powder obtained by heating the tribromide to about 140°. It is insoluble in water, but is decomposed by it, metalic gold and the tribromide being formed; the change is especially rapid on boiling, and is hastened by the presence of hydrobromic acid. Auro-auric Bromide, Au2Br4, is produced by the action of bromine on finely-divided
Gold Chloride
Table of ContentsAuro AurichlorideAuric Chloride or Gold TrichlorideChloroauric Acid Gold Monochloride or Aurous Gold Chloride “AuCl” is a salt is prepared by heating the trichloride to 185° in air for twelve hours. It is non-volatile and unaltered at ordinary temperatures and pressure by dry air, even when exposed to light, but begins to decompose at temperatures above 160°, and the decomposition is
Volatilisation of Gold
The boiling point of pure gold has not been determined; calculated according to Wiebe’s formula it would be about 2,240°, or nearly 500° above the melting point of platinum. However, contrary to the belief of the older experimenters, it is sensibly volatile in air at far lower temperatures. Robert Boyle was unaware of this fact, but Homburg gilded a silver
Gold and Copper Alloys
Gold and Copper Alloys dissolve in one another in all proportions, forming a complete series of homogeneous alloys, which are less malleable, harder, more elastic, and more fusible than gold, and possess a reddish tint. Those with less than 12 per cent, of copper are fairly malleable; when more than this is present they are more difficult to work owing
Gold and Silver Alloys
Gold and silver unite in all proportions, yielding alloys which are harder, more fusible, and more elastic than either metal. The hardest is that containing two parts of gold to one of silver. The colour of gold is sensibly lowered by the addition of very small quantities of silver, and on increasing the proportion of the latter, the colour changes
Gold Alloys
Table of ContentsLiquation of Gold AlloysGold and AluminiumGold and SilverGold and CopperLiquation of Gold Alloys Gold can alloy with almost all other metals, but most of the bodies thus formed are of little or no practical importance. Tin, zinc, arsenic and antimony unite with gold with contraction, and form pale yellow or grey coloured, hard, brittle and easily fusible alloys,
Solubility of Gold
Table of ContentsHow to Prepare Pure GoldSolubility of GoldAllotropic Forms of GoldGold Amalgams Gold is readily soluble in aqua regia, or in any other mixture producing nascent chlorine, among such mixtures being solutions of: nitrates, chlorides, and sulphates — e.g., bisulphate of soda, nitrate of soda, and common salt; chlorides and some sulphates—e.g., ferric sulphate; hydrochloric acid and potassium chlorate; bleaching
Carbon Regeneration
In normal process streams activated carbon is exposed to a variety of chemicals. Organic compounds tend to adsorb readily on the hydrophobic activated carbon, which reduces site availability for gold cyanide. Other compounds such as calcium and magnesium carbonate commonly precipitate on the carbon surface and restrict gold adsorption access. Consequently, the performance of the activated carbon decreases unless it
What Causes Leach Pad Liner Differential Settlement
Differential settlement of a leach pad liner is typically thought of being caused by consolidation of soils due to the load created by the heap materials over a soft clay soil and/or elastic compression of the subgrade soils due to this load. In these cases, the loads at the toe of the heap are essentially zero and they increase to
Types of Placers
Table of ContentsRESIDUAL GOLD PLACERSELUVIAL GOLD PLACERSSTREAM GOLD PLACERSa. Gulch placers:b. Creek placers:c. River deposits:d. Gravel-plain deposits:BENCH GOLD PLACERSFLOOD GOLD DEPOSITSDESERT GOLD PLACERSTERTIARY GRAVELS DEPOSITGOLD PLACER DEPOSIT TYPESa. Beach placers:b. Glacial PLACER GOLD deposits:c. Eolian GOLD placers:Types of Placer DepositsClassification of placer deposits (Brooks) Perhaps the best known schemes for the classification of gold placer deposits are those by Jenkins and Brooks, the former being
Gold Placer Geology
Table of Contentsa. Lodes:b. Pre-existing placers:c. Auriferous conglomerates and glacial debris:d. Magmatic segregations:e. Regional rocks:How Gold Placer Deposit Formeda. Ground water:b. Temperature:c. Plant growth:d. Surface erosion:Understanding Streams in Gold Placer FormationHow Gold Concentrates in Placer Depositsa. Bedrock concentration:b. Types of bedrock:c. Pay Streaks:Gold Placer Deposit Preservation Processa. Abandonment:b. Regional uplift:c. Burial: The source of gold or other minerals found in
Colorimetric Analysis
This method of analysis is generally applied to the determination of small percentages of an element or compound, and in this chapter the following will be considered: (a) The Colorimetric Estimation of Copper. (b) The Colorimetric Estimation of Carbon in Steel. And though not coming under this head, (c) The Volumetric Estimation of Copper by Potassium Cyanide. This last method
ASSAYING CHLORINE BY PRECIPITATION WITH SILVER NITRATE
When we consider the ordinary gravimetric precipitations, it is evident that if the exact strength (as regards precipitation) of the precipitating reagent Apparatus, Reagents.—Apparatus as usual. For the preparation of the standard solution, pure silver nitrate (preferably triple crystallized) is required. For practice in this analysis the student may first estimate the chlorine in pure sodium chloride, and then in
Analysis by Neutralisation
The measurement of the strength of an acid by the quantity of alkali required to neutralise it (termed acidimetry), and the measurement of the strength of an alkali by the quantity of acid required to neutralise it (termed alkalimetry), will be considered in this chapter. The student is asked to determine volumetrically: THE ESTIMATION OF CHLORINE IN BaCl2,2H2O VOLUMETRICALLY BY
Electrolytic Analysis
Table of ContentsProduction of the CurrenMeasurement of the Current StrengthMeasurement of the TensionElectrodes & Electrolytic CellELECTROLYTIC ESTIMATION OF COPPERMethod of AnalysisThe AnalysisTHE ESTIMATION OF COPPER IN ITS ORESELECTROLYTIC ESTIMATION OF COPPER & NICKEL IN COPPER NICKEL ALLOY The theory of electrolysis cannot be taken up at any length here, and the student desiring fuller information on this subject is referred
Assaying Lead Ores
To determine by fire-assay the percentage of lead in: (a) The sulphide. Galena (PbS). (b) An oxidised ore containing Cerussite (PbCO3), Anglesite (PbSO4), etc. (a) The sulphide, Galena Methods employed. Regarding the methods employed authorities vary widely ; here two methods are given for sulphide ores, the Soda and Argol (or Nail) method, and the Cyanide method. The reactions are expressed as follows—
What the Effect of Varying Furnace Temperatures
Table of ContentsThe Wind or Melting FurnaceThe Effect of Variations in TimeThe Effects of varying the TemperatureThe Influence of Temperature and Time on the Roasting of Sulphide OresEstimation of the Reducing Power of Charcoal, Flour, and ArgolEstimation of Silver in Litharge, Sheet and Granulated Lead The Wind or Melting Furnace Principle.—According to the equation 2PbO + C = Pb2 +
Shale Oil, Petroleum, and Lubricating Oil Analysis
Table of ContentsEXAMINATION OF SHALEPARTIAL ANALYSIS OF PETROLEUMLUBRICATING OILS The subject here touched upon is one that can only be successfully handled by an expert chemist with a thorough training in both inorganic and organic chemistry; yet, as the metallurgical chemist may be asked to value a shale or petroleum, examine an oil for lubricating purposes or for the preservation
Chemical Composition of Cements
A suitable material for the student to operate on is the well known brand —Portland Cement. As the student has already examined in detail a silicate, the following notes are given somewhat briefly. A good cement should consist chiefly of SiO2 and CaO, with a little Al2O3 and Fe2O3, and less than 2% MgO, and 1.5% CO2 and SO3. From
Coal and Coke Analysis
Table of ContentsAnalysis of CoalAnalysis of Cokes For technical purposes the following estimations may be required: Moisture, Volatile Matter, Ash, and Fixed Carbon; Sulphur, and Phosphorus. Carbon and Hydrogen by ultimate organic analysis. The calorific (or heating) power of the coal. Besides the chemical analysis of cokes, there are required the “Crushing resistance,” “Porosity,” and “Specific Gravity.” For information concerning these
Chimney / Furnace Gase Analysis
Table of ContentsApparatusAbsorption of the OxygenAbsorption of Carbon Monoxide In chimney or furnace gases the estimations usually made are the percentages by volume of oxygen, nitrogen, carbon-monoxide, and carbon-dioxide. The more refined methods of gas analysis are too slow for technical requirements, and are replaced by the Elliott, Hempel, or other methods. The method here to be described is that of Hempel, and differs chiefly
Water Analysis Methods
Table of ContentsMethod of AnalysisEstimation of Total SolidsOrganic and Volatile MatterAnalysis of the ResidueEvaluate Hardness of WaterDr Clark’S Soap TestStandard Hard WaterStandard Soap SolutionTotal HardnessPermanent Hardness In this section eight chapters are given, each dealing with one or more technical methods of analysis. The typical technical method should be quick, accurate, and inexpensive. Accuracy may to some extent be sacrificed
Fire Assay of Copper
This assay is presented here, not with the purpose of giving the student an accurate and handy means of estimating copper in its ores, but to give him some practice in manipulation, which, on the small scale, somewhat resembles metallurgical methods. In all modern mining fields the fire-assay of copper is replaced by the Volumetric or Electrolytic methods, both of
ESTIMATE SILVER IN COINAGE
For practice, a convenient material to operate on is an English silver coin, which contains 925 parts of silver to 75 parts of copper by weight. The student, therefore, knows the composition of the alloy. When dealing with alloys of unknown composition the process is more complicated (see note appended). Method.—A given weight of the bullion is cupelled with