Plate furnaces

The reaction is carried out in pot furnaces (low brick-lined hearths with lids), continuous furnaces or rotary plate furnaces. The melt produced in the furnace is mashed with water, the undissolved material removed and the solution concentrated to 60 to 62% sodium sulfide by evaporation in cast iron vessels. This concentrated solution solidifies at ca. 90°C. 

Sodium dichromate is reduced with sulfur by intensively mixing the components and then calcining in rotary kilns or rotary-plate furnaces at 800 to 1000°C. 

Ensure that prominent signs warning workers against hot areas such as vents, hot plates, furnaces, water baths, and digestion apparatus are posted in the work area. 

The success of the process results from the fact that nowhere inside the furnace is heat extracted from the copper-saturated blast furnace buUion through a soUd surface. The problem of accretion formation (metal buUd-up), which has plagued many other attempts to estabUsh a copper dtossing operation of this type, does not arise. In the cooling launder, lead-rich matte and slag accumulate on the water-cooled plates, but these ate designed so that when they ate lifted from the buUion stream, the dross cracks off and is swept into the furnace via the cooled lead pot. 

Low Phosphorus Pla.te a.nd Punchings. This scrap, a prompt iadustrial scrap consisting of punchings or stampiags, plate scrap, and bar croppiags, has uniform known chemical analysis, is clean, and has high furnace recovery (5aeld) when melted. Maximum allowable phosphoms and sulfur contents are 0.05% each. Other unwanted residual elements are also uniformly low. Size limitations are specified. 

Top-Blown Basic Oxygen Process. The top-blown basic oxygen process is conducted ia a cylindrical furnace somewhat similar to a Bessemer converter. This furnace has a dished bottom without holes and a tmncated cone-shaped top section ia which the mouth of the vessel is located. The furnace shell is made of steel plates ca 50-mm thick it is lined with refractory 600—1200-mm thick (11). 

Recycling of antimony provides a large proportion of the domestic supply of antimony. Secondary antimony is obtained from the treatment of antimony-hearing lead and tin scrap such as battery plates, type metal, beating metal, antimonial lead, etc. The scrap are charged iato blast furnaces, reverberatory furnaces, or rotary furnaces, and an impure lead bulHon or lead alloy is produced. Pure lead or antimony is then added to meet the specifications of the desired lead—antimony alloy. 

To reduce labor and other expenses, most sintered nickel plaques are produced by a wet-slurry method. A nickel slurry is prepared by mixing a low density nickel powder with a viscous aqueous solution such as carboxymethylceUulose [9004-42-6] (CMC). Pure nickel gau2e, a nickel-plated gau2e, or a nickel-plated perforated steel strip is continuously carried through a container filled with the nickel paste and sintering is done in a hori2ontal furnace. The time of the sinter in the furnace is ca 10—20 min. 

Carbon Electrodes. Carbon electrodes are rigid carbonaceous shapes deployed in electric furnaces. They are the final link in the chain of conductors from the energy source to the reaction zone of an electrically heated vessel. The gap bridged by the electrode is that between the contact plates that transmit current to the electrode and the discharge area at the arc end of the electrode. 

Self-baked carbon electrodes are those whose shapes are formed in situ (33). The carbonaceous mixture is placed into a hoUow tube-shaped metal casing. The upper end receives the unbaked mixture as a soHd block, small particles, or warm plastic paste. The casing contains inwardly-projecting longitudinal perforated fins that become surrounded by baked carbon as the casing is incrementally moved downward and through the contact plates. Casing and carbon are consumed in this furnace. 

Ash. After the sample is heated ia a cmcible over a hot plate to drive off volatile solvents and moisture, it is charred over a Bunsen burner and then transferred to a muffle furnace where final ignition is completed. The weight of the ash is determined and reported as a percentage of the weight of the original sample. 

Typical applications in the chemical field (Beaver, op. cit.) include detarring of manufactured gas, removal of acid mist and impurities in contact sulfuric acid plants, recovery of phosphoric acid mists, removal of dusts in gases from roasters, sintering machines, calciners, cement and lime Idlns, blast furnaces, carbon-black furnaces, regenerators on fluid-catalyst units, chemical-recoveiy furnaces in soda and sulfate pulp mills, and gypsum kettles. Figure 17-74 shows a vertical-flow steel-plate-type precipitator similar to a type used for catalyst-dust collection in certain fluid-catalyst plants. 

Hydrogen cyanide From metal plating, blast furnaces, dyestuff works Metal fabricating, primary metals, textiles Capable of affecting nerve cells... 

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