0.-3

134

Subject B. — Amalgamating ana chines, 1. Give fully a description of the amalgamating-machines you have used. Give their speed, their capacity, and the horse-power required to work them. Also .state where you would place them in a crushing-battery in relation to the stamp-mortars. 2. Describe the class of auriferous ore suitable for concentration; also give a description of ore unsuitable for treatment by that process. Give your reasons fully. 3. What effect, if any, has heat on the amalgamation of bullion contained in ore? How is heat applied to amalgamating-machines; and what temperature would you consider most suitable for the amalgamation of bullion in the ore? Describe fully. 4. Describe the action of berdans, Wheeler's pans, combination pans, and Boss pans. State the quantity of pulverised ore each is capable of treating in twenty-four hours, the quantity of quicksilver u.sed in each, the speed at which each is driven, and the horse-power required to work them. Subject C. — The Use of Quicksilver, and Methods of using it in connection with the Extraction of Gold and Silver from Ores. 1. What is meant by the "sickening" of quicksilver? (a.) How is it caused? (6.) How do 3 - ou ascertain that quicksilver is sickened? (c.) What precaution would you take to prevent the sickening of quicksilver? (d.) How would you remove the impurities from quicksilver? Describe fully. 2. How is amalgamation effected b}» copper or muntz-metal plates? (a.) How are the plates prepared? (6.) How is the bullion removed from the plates? (c.) State the length, width, thickness, and gradient at which plates are laid down for amalgamating purposes in a stamp-battery. 3. What effect, if any, had sodic chloride (NaCl) arid cupric sulphate in the amalgamation of bullion in auriferous and argentiferous ores; and how is it applied? 4. How is gold and silver removed from quicksilver, and put into ingots fit for market? Give a description of the whole process from the time the ore is submitted to the action of quicksilver until the precious metals are in a marketable condition Subject D.— Cyanide, Chlorination, and, other Chemical Processes of recovering Gold and Silver from Ores. ' 1. State fully the class of ore you consider best suited for treatment with KCN solutions; also the class of ore most suitable for treatment by chlorination; and give your reasons for same. 2. Describe fully how you would test the strength of KCN solutions, and how j'ou would make up stock solutions. 3. If you had to make up 30 tons of a o'2-per-cent. KCN solution, using 25 tons of a sump solution containing o'o9 per cent, of KCN, how many pounds of crude cyanide containing 76 per cent. KCN would you require to make the solutions up to the required strength? 4. How many tons of a 5-per-cent. KCN solution would be required to make up 40 tons of a 0-3-per-cent. solution, using a sump solution containing o'os per cent. KCN? 5. Describe fully how KCN solutions are applied to pulverised ore: (a) The condition of the ore before being subjected to KCN solutions; (b) how the vats are filled with ore, and how the KCN solutions are used; (c) how the solutions are drawn off; (d) how it is ascertained when the ore has been completely treated. 6. Describe how you would ascertain the best strength of KCN solutions for the treatment of any particular class of ore. 7. Show by calculation the cubic contents of a vat 32 feet in diameter and 8 feet 4 inches deep. 8. Describe fully the process of recovering the bullion from slimes subjected to KCN solutions, from the filling of the agitator-vats until the bullion is precipitated in the zinc extractors. 9. State fully what remedies you would apply in the case of any workman showing signs of KCN poisoning. 10. Describe the Siemens-Halske process for the electrical precipitation of gold from KCN solutions. 11. How is the chlorination of ores effected? (a.) How is chlorine gas produced? (6.) How long is ore subjected to chlorination by the Newbery-Vautin process? (c.) How is the gold precipitated and dealt with before it is in a marketable condition? 12. Describe fully how the gold is recovered from the zinc extractors and put in a fit state for market. Subject E.— Sampling and, Testing of Ores 1. Describe how you would take a sample for assay— (a) from a large heap of tailings, (b) from a truckload of ore as it comes from the mine. 2. How would you estimate the copper in a sample of pyrites? 3. Describe (a) a " wet " method and (6) a " dry " method of determining lead in galena. 4. Describe exactly how you would determine the presence of the various elements if given a sample of rock containing sulphides of silver, copper, arsenic, iron, and nickel.