To these leached guanos and phosphatized limestones the name sombrerite has been given.
The residue, consisting of alumina and potassium sulphate, was leached with water to separate the insoluble matter which was dried as usual.
Of a metalliferous vein is generally more or less altered by oxidation, and often a part of the valuable mineral has been converted into a soluble form and leached out.
The liquors are run off from the vats to the electrolysing baths or precipitating tanks, and the leached ores are removed by means of doors in the sides of the vats into wagons.
Siemens and Halske introduced a combined process in which the ore, after being part-roasted, is leached by solutions from a previous electrolytic operation, and the resulting copper solution electrolysed.
The solution is removed by ladles or by siphons, and the residue is leached out with boiling water; this removes the sulphates.
The leached guanos and phosphatized rocks, which are grouped with them for commercial purposes, have been obtained in great quantities in many islands of the Pacific Ocean (such as Baker, Howland, Jarvis and McKean Islands) between long.
In the West Indies from Venezuela to the Bahamas and in the Caribbean Sea many islands yield supplies of leached guanos; the following are important in this respect: Sombrero, Navassa, A y es, Aruba, Curacoa.
On permeable soils, especially those of the terrace lands along the valleys, the soluble salts commonly known as alkali were gradually leached out and carried by the percolating waters towards the lower lands, where, reaching the surface, the alkali was left as a glistening crust or as pools of inky blackness.
As a rule the ore is subjected to a preliminary chloridizing roast, though occasionally it may be leached raw.
Deep if the leached ore is to be removed by sluicing, 5 ft.