Manhès–David process

Inspired by the Bessemer process, it consists of the use of a converter to oxidise with air the undesirable chemical elements (mainly iron and sulfur) contained in the matte, to transform it into copper.

The quantity of the elements to be oxidized, as well as the low heat produced by the chemical reactions, lead to drastics modifications of the converter.

A few years later, the Americans engineers William H. Peirce and Elias Anton Cappelen Smith lined it with basic refractory materials, much more durable than that used by the French inventors.

While this improvement does not alter the principles of the process, it eases its widespread use, accelerating the switchover of copper production from Britain to the United States.

[2] The refinement of the alloy in the converter is possible because the combustion of undesirable elements is strongly exothermic: the oxidation of silicon and carbon respectively produce 32.8 and 10.3 kilojoules per kilogram.

[3] On the other hand, if a copper matte contains an abundance of iron and sulfur, these elements must first be separated (which consumes 6.8 kilojoules per kilogram of FeS) before their oxidation (which only produces 5.9 and 9.1 kJ/kg respectively) can begin.

The oxidation of undesirable elements occurred as expected, but the operation was quickly disrupted by the appearance of metallic copper.

He proposed horizontal tuyeres placed at a sufficient distance from the bottom of the converter so that the copper could gather below them and the air blow constantly in the matte.

[8] As the slag becomes enriched with iron oxide during the reaction in air, it becomes basic and then combines with the siliceous refractory lining, which is very acidic.

The adoption of a lining inspired by one developed by Sidney Thomas and Percy Gilchrist in 1877[12] was suggested by Hollway during his last tests in the early 1800s.

[6] In 1890, a basic refractory lining was tested on one of Parrot Smelter's Manhès-David converters, in Butte, under the direction of Herman A. Keller.

[2] In 1906, Ralph Baggaley, still in Montana, succeeded, after a number of tests, in industrializing a basic coating at Pittsmont Smelter, which was abandoned in 1908 after he left the factory.

[2] By developing a masonry suitable for the cylindrical converter and increasing the amount of metal fed into the furnace, they solved the remaining problems.

Alignment of 10 Manhès-David converters of the Canadian Copper Company , at Greater Sudbury , before 1911. These converters refined a matte with 36% Ni+Cu, in a matte containing 80% Ni+Cu. [ 1 ]
Converters from the Inspiration Consolidated Copper Company in 1972. The second converter is a vertical type. The green flame that comes out of it is characteristic of the combustion of iron(II) sulfide (FeS).