Copper Coarse

Estimatiofi of Niiroo-ot, Second Method.—Another method w hich dispenses with the small furnace and bicarbonate tube may also be used. The long combustion tube is closed at one end and magnesite m small lumps is introduced into the tube and shaken down to the closed end until there is a layer of about 13- 15 cm. (5—6 in.). This is kept in place by a plug of asbestos and the tube is filled s-uccessively with 5 cm. (2 in.) of coarse copper o.xide, then fine copper oxide mixed with the substance, a further layer of coarse copper oxide, and finally the... 

Prepare the copper oxide-lead chromate as follows Spread a thin layer of coarse copper oxide over a small iron plate, heat from above with a blow pipe until the glow is as bright as possible and sprinkle with a thin layer of finely powdered lead chromate. The chromate melts at once and spreads over the copper oxide forming a firmly adherent layer and causing the strips of copper oxide to stick together a little. Now turn the cake over and treat the under side in the same way. When the mass has cooled break it up gently in a mortar and remove powder and unduly large pieces with a sieve. 

The process for electrowinning of copper is schematically shown in Fig. 12.9. If copper(I) sulfate in AN-H20-H2S04 solution is electrolyzed using a platinum electrode as anode and a copper electrode as cathode, one-electron processes occur at the two electrodes (Cu1 —> Cu2 at the anode and Cu1 —> Cu° at the cathode). Compared with the conventional electrowinning from the aqueous acidic solution of copper(II) sulfate (water oxidation at the anode and Cu2+ —> Cu° at the cathode), the electric power consumed is only about 10% and high-quality copper can be obtained. It is of coruse necessary to return Cu2+, generated at the anode, to Cu+. But various methods are applicable to it, e.g., by the contact with coarse copper. 

In the electrorefining of copper, copper(I) sulfate in the AN-H20-H2S04 solution is electrolyzed using a coarse copper electrode as anode and a pure copper electrode as cathode. The reaction at the anode is Cu° —> Cu+, while that at the cathode is Cu+ —> Cu°. Compared to the conventional process which uses aqueous acidic solutions of copper(II) sulfate, this method is advantageous in that the quantity of electricity is one-half and the electric power is also small. Moreover, the low quality AN used in this method is available at low price and in large quantity as a by-product of chemical industries. 

Several methods are applicable to the production of cupric sulphate on the manufacturing scale. Old copper plates are heated with excess of sulphur to bright redness in a reverberatory furnace with closed doors until combination is complete. The doors are then opened, and the mass is oxidized at dull-red heat. When oxidation is complete, the hot product is transferred into dilute sulphuric acid, and the dear solution concentrated after decantation. The crystals formed are of a moderate degree of purity. The process is also applicable to coarse copper, and to copper-glance and other sulphur ores or copper. 

It was Pliny (1. 34, c. 2) who first taught that coarse copper scales differed from Flower of Copper, when he said Now these scales come by being driven and smitten off from those bars which they use to forge of the said masses and lumps of copper, and all these most commonly are found in the Cyprian forges herein only is the difference, that the aforesaid scales are driven forcibly from the masses of copper, whereas the flower of verdigris fails off by itself And yet there is a second kind of these scales, more fine and subtle than any other, to wit, driven and smitten from the very outside and uppermost part of the bar, and this they call Stomoma. He adds that both the one and the other are calcined either over earthen or brazen vessels, and afterwards washed. Finally, he also avers that the scales made of the white metal are indefinitely less efficacious. But neither the scales nor the flower are used by our doctors as they were in the time of Pliny. 

The coarse copper oxide is not previously heated in the nickel crucible as in the determination of nitrogen, but this is done later in the tube itself. If the nature of the substance to be analysed is such that it is necessary to mix it with fine copper oxide, the latter is ignited for a quarter hour in the porcelain crucible and allowed to cool in a desiccator. 

The separation of the germ, gluten and starch is accomplished in the wet process by the reels. These are long open cylinders covered with perforated copper or silk depending upon the work to be done by the reel. The grams are separated by the coarse copper reels. The starch is separated from the coarse and fine feed, by file coarse feed reels, the No. 9, the No. 12 and the No. 17 silk reels. Sometimes even No. 20 silk reels are used. 

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