Acid-proof bricks

Among nonmetallic materials, glass, chemical stoneware, enameled steel, acid-proof brick, carbon, graphite, and wood are resistant to iodine and its solutions under suitable conditions, but carbon and graphite may be subject to attack. Polytetrafluoroethylene withstands Hquid iodine and its vapor up to 200°C although it discolors. Cloth fabrics made of Saran, a vinyHdene chloride polymer, have lasted for several years when used in the filtration of iodine recovered from oil-weU brines (64). 

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. 

Depending on the technical requirements such as corrosion resistance, pressure and temperature stability, industrial scale azo pigment synthesis is carried out in appropriate equipment. Suitable materials include cast iron, stainless steel, steel lined with rubber, acid-proof brick, enamel, synthetic resins supported by glass fiber, and wood. 

Iodine is packed and supplied in polyethylene-lined fiber drums or high sihcon iron, Hastelloy B, or lead coated steel containers. Glass, graphite and acid-proof bricks are very suitable for storing iodine and its solutions. 

Duro. Tradename of Harbi son-Walker Refractories Co, Pittsburgh, Pa for an acid-proof brick made from materials of very low flux content. When fired stable minerals are formed which are in sol in various acids and in other corrosive liquids used in tanks storing acids, supports for acid tower packing, etc... 

Also Reed [7] described a method of nitrating phenolsulphonic acids in a large pot nitrator of 5500 1. capacity made of acid-proof bricks. Picric acid was settled in a wooden, lead-lined slurry tank and eventually separated in a centrifuge. 

Acid Brick Acid brick, also called acid resistant or acid proof brick (covered by ASTM C279), are of two major types (1) Red shale, the predominant brick in CRM construction and (2) Fireclay, another common brick in CRM applications. These two acid brick are the most widely used masonry units in CRM structures and linings, including floors, trenches, sumps, vessels and chimney... 

McDowell, D.W., Jr. and Sheppard, W.L., Jr., Using Acid-Proof Brick and Mortar in Masonry Construction and Picking Nonmetailic Construction Materiaisto Resist Mineral Acid Attack,Plant Eng. (2/19/76 3/18/76). 

Sometimes it is necessary to apply acid-proof brick or monolithics such as trowelled epoxies to a steel decking. This practice is not recommended for the following reasons ... 

If the designer decides to protect a steel deck with acid-proof brick, he should consider the following recommendations ... 

Evaporators are usually built with cast-iron or steel shells and with wrought-iron tubes. Sometimes, where the liquor is not quite neutralized, copper tubes are to be preferred. In special cases where the waste liquor is not neutralized at all, all copper construction is necessary, which may be replaced by evaporator shells of cast-iron or steel with acid-proof brick lining and copper tubes. 

Use Wetting agent, furan polymers, corrosion-resistant sealants and cements, foundry cores, modified urea-formaldehyde polymers, penetrant, solvent for dyes and resins, flavoring. The polymer is used as a mortar for bonding acid-proof brick and chemical masonry. 

Absorption trains of early ammonia oxidation processes to nitric acid were constructed of chemical stoneware or acid-proof brick, which restricted acid production to near ambient atmospheric pressure because of the low strength of the structural materials. The discovery that Duriron (silicon-iron) or high chrome stainless steels could tolerate these corrosive conditions well allowed the adoption of pressure absorption. This measure markedly decreased the size of the absorbers required and reduced nitrogen oxide stack losses. Pressure operation was easiest to achieve by compression of the feed gases at the front end of the process. In this way improved acid production is obtained at comparable capital costs per unit of product by operation at atmospheric pressure. 

With the increase in cost of refractories, acid proof bricks, special quality mild steel, boiler tubes, alloy steels, etc., an innovative process is emerging in the manufacture of sulfuric acid and sulfonating agents. 

It is interesting that alumina-silica bricks are attacked by acids in chemical applications at room temperature. For example, 70% AI2O3 bricks have been known to exhibit service of only several weeks in hot hydrochloric and sulfiulc acids. Acid-proof bricks are commonly used in chemical service, and these bricks last longest if they exhibit extremely low apparent porosities and if then-composition exhibits extremely low alkalis. Alkali phases form glasses in manufacturing that are more readily soluble in acid media, so the bond phase in acid-proof brick must contain higher alumina content and lower alkali content. 

F. are mainly used in core binders (- foundry industry) but also to make corrosion-restistant mortars and concrete (installation of acid-proof bricks) and in laminating for corrosion- and heat- resistant fiberglass-reinforced equipment. 

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