Furnace vertical retort

At first, batchwise horizontal retorts were used for smelting, and later continuous vertical retorts, both externally fired. Continuous, internally heated furnaces such as the electrothermic furnace followed, and the last important development was the Imperal Smelting blast furnace. 

These formerly involved the use of banks of externally heated, horizontal retorts, operated on a batch basis. They were replaced by continuously operated vertical retorts, in some cases electrically heated. Unfortunately none of these processes has the thermal efficiency of a blast furnace process (p. 1072) in which the combustion of the fuel for heating takes place in the same chamber as the reduction of the oxide. The inescapable problem posed by zinc is that the reduction of ZnO by carbon is not spontaneous below the boiling point of Zn (a problem not encountered in the smelting of Fe, Cu or Pb, for instance), and the subsequent cooling to condense the vapour is liable, in the presence of the combustion products, to result in the reoxidation of the metal ... 

The furnace at Portsmouth was installed in the Conservation Department of the City Museum in 1975. The design of the furnace was influenced by the considerable number of large cannons recovered from the Solent and in particular, from the Mary Rose. It was a vertical retort furnace with a cylindrical bell type retort 2.5 m high by 0.7 m in diameter made of Nimonic, a heat resistant alloy. Once loaded with the artefacts, the retort was wheeled into an electrically-heated furnace with three banks of independently-controlled... 

Some vapor-phase materials are prepared from hard starting materials, For nutshells, the procedure used is to calcine Che shells, gmauiate to size, and activate. In the case of ccel or charconl, the material is ground to powder, bonded with pitch and formed, calcined a( 500-700°C. and activated wirh steam or flue gas at 500-950°C. The high-temperature furnaces employed include kilns, multiple-hearth, and vertical retort. 

Figs. 24 and 25 show Castner s sodamide furnace. It consists of an iron retort, the upper part of which is provided with a series of vertical baffle plates C, arranged as indicated. The retorts are heated to 300°-400° C., ammonia entering at N and molten metallic sodium at D, while the fused fuel products can be run off by K. 

Rexco (700°C) made in cylindrical vatical retorts. Coalite (650°C) made in vertical tubes Town gas and gas coke (obsolete). Phurnacite, low volatile steam coal, pitch-bound briquettes carbonized at 800°C Foundry coke (900°C) blast furnace coke (950°C-1050°C)... 

The apparatus (Fig. 36) was very elaborate and only part of it is reproduced here. The iron retort was heated in a furnace and was connected by a luted joint with a wide tube passing through the wall of a wood or metal trough filled with water. This tube ended in a sphere, from which a vertical tube passed inside a tall bell-jar filled with water, the surface of which was covered with oil. Lavoisier says this apparatus is adapted from Hales s by Rouelle, with some changes and additions made by himself (he could have seen it in Rouelle s lectures). 

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