A certain amount of bismuth sulphate is always formed during the calcination; this is subsequently reduced to the sulphide and ultimately to the metal in the fusion.
A third class of furnaces is so arranged that the work is done by indirect heating; that is, the material under treatment, whether subjected to calcination, fusion or any other process, is not brought in contact either with fuel or flame, but is raised to the proper temperature by exposure in a chamber heated externally by the products of combustion.
According to Egleston the loss may be from 40 to 90% of the total gold present in cupriferous ores according to the temperature and duration of calcination.
Also, however slowly the calcination may be conducted, there is always more or less copper sulphide left unchanged, and some copper oxide formed.
Both processes are inferior in economy to calcination in rotatory kilns, a process which may be regarded as the method of the present and the immediate future.
Calcination in reverberatory furnaces and a subsequent smelting in the same type of furnace with the addition of about 3% of coal, lime, soda and fluorspar, has been adopted for treating the Bolivian ores, which generally contain the sulphides of bismuth, copper, iron, antimony, lead and a little silver.
Calcination is only advisable for ores which contain relatively much iron pyrites and little copper pyrites.
He established as fundamental that combustion and calcination were attended by an increase of weight, and concluded, as did Jean Rey and John Mayow in the 17th century, that the increase was due to the combination of the metal with the air.
It may also be accomplished by calcination with ferrous sulphate, or other easily decomposable sulphates, such as aluminium sulphate.
Jeweller's rouge for polishing plate is a fine red iron oxide prepared by calcination from ferrous sulphate (green vitriol) .
Jeweller's rouge for polishing plate is a fine red iron oxide prepared by calcination from ferrous sulphate (green vitriol).
Metals on calcination gave calces from which the metals could.
Sulphuretted ores are smelted, either with or without a preliminary calcination, with metallic iron; calcined ores may be smelted with carbon (coal).
The calcination is preferably effected in mechanical roasters, it being especially necessary to agitate the ore continually, otherwise it cakes.
The calcination, or roasting, is conducted at a low temperature in some form of reverberatory furnace.
The carbonic acid gas injected into the highly limed juice in the saturators is made by the calcination of limestone in a kiln provided with three cleaning doors, so arranged as to allow the lime to be removed simultaneously from them every six hours.
The conversion into sulphate is generally effected by the oxidizing processes of weathering, calcination, heating with iron nitrate or ferric sulphate.
The phlogistic theory of the processes of calcination and combustion necessitated the view that many acids, such as those produced by combustion, e.g.
The phlogistic theory, which pervaded the chemical doctrine of this period, gave rise to continued study of the products of calcination and combustion; it thus happened that the knowledge of oxides and oxidation products was considerably developed.
The quicklime as quarried from the bluffs slakes perfectly, and with sand makes a fairly good mortar, without calcination or other previous preparation.
The reactions are strictly analogous to those which occur in the smelting of galena (see Lead), the carbon reducing any oxide, either present originally in the ore or produced in the calcination, and the iron combining with the sulphur of the bismuthite.
The study of calcination and combustion during the 17th and 18th centuries culminated in the discovery that air consists chiefly of a mixture of two gases, oxygen and nitrogen.
Then, perceiving that in combustion and the calcination of metals only a portion of a given volume of common air was used up, he concluded that Priestley's new air, air eminemment pur, was what was absorbed by burning phosphorus, &c., "non-vital air," azote, or nitrogen remaining behind.
This is effected by calcination or roasting.
This lime is charged in the form of common quicklime, CaO, resulting from the calcination of a pure limestone, CaCO 3, which should be as free as possible from silica.
Using in-situ synchrotron measurements to follow the calcination of a (TiO 2) 0.18 (SiO 2) 0.82 sol-gel.