Brick lining

Depending on the chemical nature of the slurry to be filtered, materials of constmction include wood, plastics, earthenware, steel, lead-lined steel, and brick-lined cast iron. 

Most of the magnesium is cast iato iagots or billets. The refining of the molten metal extracted from the electrolysis is performed continuously ia large, stationary brick-lined furnaces of proprietary design (25). Such iastaHations have a metal yield better than 99.5% and negligible flux consumption. 

Equipment. The standard equipment in magnesium foundries consists of large stationary brick-lined reverbatory furnaces which can hold up to 10—15 t of molten magnesium. Reverbatory furnaces are furnaces in which heat is suppHed by burning a fuel in a space between the reactants and the... 

Fig. 2. Downs cell A, the steel shell, contains the fused bath B is the fire-brick lining C, four cylindrical graphite anodes project upward from the base of the cell, each surrounded by D, a diaphragm of iron gau2e, and E, a steel cathode. The four cathode cylinders are joined to form a single unit supported on cathode arms projecting through the cell walls and connected to F, the cathode bus bar. The diaphragms are suspended from G, the collector assembly, which is supported from steel beams spanning the cell top. For descriptions of H—M, see text.

Absorption and Drying Towers. Towers are typically carbon steel vessels lined with acid proof brick and mortar and packed with ceramic saddles (see Absorption). More recently, all metal towers having no brick lining have been built from high siHcon stainless steel alloys such as Sandvik SX or Saramet. 

A conventional circular-wedge roaster consists of a brick-lined steel shell with hearths arched gendy upward from the periphery to a central shaft. The brick hearths may number from 8 to 16 and are ca 1 m apart. The central steel shaft (ca 1.2 m in diameter) revolves at 1 rpm or less carrying two rabble arms per hearth. These rabbles, cooled with air or water, plow the ore from the outside to the center of the hearth where it is dropped to the next hearth for plowing in the opposite direction. The calcine thus proceeds to the bottom where it is dropped into a conveyor. The sulfide sulfur at this point is ca 3.5% (22). 

Anhydrous Borax. Anhydrous borax is produced from its hydrated forms, borax decahydrate or pentahydrate, by fusion (Pig. 6). Low temperature calcining is usually an intermediate step to remove water of hydration. This material is fed to a refractory brick-lined furnace and fused to a mobile Hquid at about 1000°C. 

Roasting . Roasting has been largely abandoned ia modem copper smelters, ia which this function is combiaed with the smelting furnace. In older systems, the multiple-hearth roaster is a brick-lined tower having horizontal brick hearths. The concentrate is iatroduced at the top hearth, where rotating arms with rabble blades turn it over and move it to holes ia the hearth. The concentrate is transferred successively to lower hearths and finally... 

Ceramic or carbon-brick linings are frequently used as facing linings over plastic or membrane linings when surface temperatures exceed those which can be handled by the unprotected materials or when the membrane must be protec ted from mechanical damage. This type of construction permits processing of materials that are too corrosive to be handled in low-cost metal constructions. 

Brick Construction Brick-lined construction can be used for many severely corrosive conditions under which high alloys would fail. Common bricks are made from carbon, red shale, or acidproof refractory materials. Red-shale brick is not used above 175°C (350°F) because of spalhng. Acidproof refractories can be used up to 870°C (1,600°F). 

Brick linings with Absorption of the corrosive by the masonry (use membrane... 

Membranes are applied directly to the metal or concrete surface to protect from corrosion by any liquor that penetrates the brick lining through pores and cracks. Membranes consist of sheet material bonded to the metal or concrete, e.g., flexible PVC sheet, or it may be formed in situ (e.g., polyester resin reinforced with glass fiber, or synthetic rubber sheet, lead, polyisobutylene, polyethylene and asphalt). 

Brick lining (40-65 mm thick) is used for reducing the temperature at the membrane. This protects the membrane from deteriorating with free access of the process liquors and prevents its erosion and other mechanical damage [51,52]. 

Acid-Proof Vessel Ccvtisrrucfkin with Membrane and Brick Linings, N.-5CI Committee Report, Co.w.s/on i 95l-204t (March 1957),... 

The shell may be of metal (steel, alloy, or non-ferrous), plastic, wood or some combination which may require the addition of liners or inner layers of rubber, plastic or brick. The mechanical problems of attaching inner nozzles, supports and brick require considerable attention that is not an integral part of sizing the equipment. Figures 9-2A-C show a typical large steel brick-lined-membrane lined tower with corbeled brick support locations. In these towers, temperature and/or corrosive conditions usually dictate the internal lining, and the selection of the proper acid- (or alkali-) proof cements. 

The slime is recovered and heated in a brick-lined tank to melt the sulfur. The molten sulfur is filtered in a heated stainless-steel pressure filter to separate remaining nickel sulfide pieces and insoluble precious metals, and cast into moulds. The residue is remelted and cast into anodes, the resulting anode slime is now a relatively concentrated precious metal residue and is treated for the extraction of individual metals. 

In a multiple-hearth roaster, the concentrate drops through a series of nine or more hearths stacked inside a brick-lined cylindrical column. As the feed concentrate drops through the furnace, it is first dried by the hot gases passing through the hearths and then oxidized to produce calcine. Multiple hearth roasters are unpressurized and operate at 700°C (1300°F). 

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