Barium carbonates

Economic Importance. After barium sulfate, barium carbonate, which occurs naturally as witherite, is the most important barium compound. The USA production of synthetic barium carbonate, including barium hydroxide, was ca. 25 10 t in 1996. 

Manufacture In barium carbonate manufacture from barium sulfate (heavy spar) (see Fig. 3.1-3), the heavy spar is first crushed and pulverized then reduced with coke to barium sulfide at 1000 to 1200°C in a rotary tube furnace. The barium sulfide is then leached from the ground melt with hot water and the solution either reacted with carbon dioxide or sodium carbonate, whereupon barium carbonate precipitates out  

BaCOjis after natural BaS04 the most important barium compound 

Applications The most important utilization sector for barium carbonate is the manufacture of clay tiles and ceramic products, the addition of barium carbonate hindering the bleeding of salts (sodium and calcium sulfate). In the USA 30% of the consumption is devoted to this use. A further 30% is consumed in the glass industry (e.g. for the manufacture of optically special glasses and television screens). About 20%i is used in the manufacture of other barium compounds. Other uses are in special 

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Simple examples of WLN are C2H5OH is Q2 CH3C0 0CH3 is IVOl For branch chain and fused ring structures rules determine the order of notation. It is claimed that over 50% of all organic structures can be represented by less than 25 characters, witherite, BaCOj. The white mineral form of barium carbonate. Used as a source of Ba compounds and in the brick and ceramic industries. 

Barium sulphate is frequently used as a support for the palladium (compare the Rosenmund reduction of add chlorides. Section IV.120) barium carbonate... 

ALCOHOLS,HIGHERALIPHATIC - SURVEYAND NATURAL ALCOHOLSMANUFACTURE] (Vol 4) -in barium carbonate mgf [BARIUM COMPOUNDS] ( 7ol 3)... 

Inorganic Methods. Before the development of electrolytic processes, hydrogen peroxide was manufactured solely from metal peroxides. Eady methods based on barium peroxide, obtained by air-roasting barium oxide, used dilute sulfuric or phosphoric acid to form hydrogen peroxide in 3—8% concentration and the corresponding insoluble barium salt. Mote recent patents propose acidification with carbon dioxide and calcination of the by-product barium carbonate to the oxide for recycle. 

The commercial product is a dull yeUow powder containing about 90% Ba02 and about 8.5% active oxygen the remainder is mainly barium carbonate and barium hydroxide. The principal use is in pyrotechnics, but there are also small uses in the curing of polysulftde mbbers and in the production of certain titanium—aluminum alloys. 

The iodate is a poison potassium iodide, however, is used in foodstuffs. Thus the iodate must be completely removed frequently by a final reduction with carbon. After re-solution in water, further purification is carried out before recrystallization. Iron, barium, carbonate, and hydrogen sulfide are used to effect precipitation of sulfates and heavy metals. 

Alkali moderation of supported precious metal catalysts reduces secondary amine formation and generation of ammonia (18). Ammonia in the reaction medium inhibits Rh, but not Ru precious metal catalyst. More secondary amine results from use of more polar protic solvents, CH OH > C2H5OH > Lithium hydroxide is the most effective alkah promoter (19), reducing secondary amine formation and hydrogenolysis. The general order of catalyst procUvity toward secondary amine formation is Pt > Pd Ru > Rh (20). Rhodium s catalyst support contribution to secondary amine formation decreases ia the order carbon > alumina > barium carbonate > barium sulfate > calcium carbonate. 

One commercial process for producing sodium sulfide is as a by-product of barium carbonate production (see Barium compounds). Barite ore, BaSO, is reduced with carbon at 800°C to produce cmde barium sulfide (black ash), which is then leached to dissolve the barium sulfide in solution. The solution is then reduced using sodium carbonate to produce barium carbonate, leaving a weak sodium sulfide solution as the by-product. The sodium sulfide solution may then be concentrated and flaked or crystallized. 

The main electroceramic apphcations of titanium dioxide derive from its high dielectric constant (see Table 6). Rutile itself can be used as a dielectric iu multilayer capacitors, but it is much more common to use Ti02 for the manufacture of alkaline-earth titanates, eg, by the cocalciuation of barium carbonate and anatase. The electrical properties of these dielectrics are extremely sensitive to the presence of small (<20 ppm) quantities of impurities, and high performance titanates require consistently pure (eg, >99.9%) Ti02- Typical products are made by the hydrolysis of high purity titanium tetrachloride. 

Alkaline-Earth Titanates. Some physical properties of representative alkaline-earth titanates ate Hsted in Table 15. The most important apphcations of these titanates are in the manufacture of electronic components (109). The most important member of the class is barium titanate, BaTi03, which owes its significance to its exceptionally high dielectric constant and its piezoelectric and ferroelectric properties. Further, because barium titanate easily forms solid solutions with strontium titanate, lead titanate, zirconium oxide, and tin oxide, the electrical properties can be modified within wide limits. Barium titanate may be made by, eg, cocalcination of barium carbonate and titanium dioxide at ca 1200°C. With the exception of Ba2Ti04, barium orthotitanate, titanates do not contain discrete TiO ions but ate mixed oxides. Ba2Ti04 has the P-K SO stmcture in which distorted tetrahedral TiO ions occur. 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

The first report concerning barium compounds occurred in the early part of the seventeenth century when it was noted that the ignition of heavy spar gave a peculiar green light. A century later, Scheele reported that a precipitate formed when sulfuric acid was added to a solution of barium salts. The presence of natural barium carbonate, witherite [14941-39-0] BaCO, was noted in Scodand by Withering. 

Barium acetate [543-80-6] Ba(C2H202)2, crystallines from an aqueous solution of acetic acid and barium carbonate or barium hydroxide. The level of hydration depends on crystallization temperature. At <24.7°C the trihydrate, density 2.02 g/mL is formed from 24.7 to 41 °C barium acetate monohydrate [5908-64-5] density 2.19 g/mL precipitates and above 41 °C the anhydrous salt, density 2.47 g/mL results. The monohydrate becomes anhydrous at 110°C. At 20°C, 76 g of the monohydrate dissolves in 100 g of water. Barium acetate is used in printing fabrics, lubricating grease, and as a catalyst for organic reactions. 

Most barium compounds are prepared from reactions of barium carbonate [513-77-9] BaCO, which is commercially manufactured by the "black ash" process from barite and coke ki a process identical to that for strontium carbonate production. Depending on the co-product, soda ash and/or carbon dioxide are also consumed. 

Precipitated or synthetic barium carbonate is the most commercially important of all the barium chemicals except for barite. Barium carbonate is an unusually dense material, that is almost kisoluble ki water and only slightly soluble ki carbonated water. It does dissolve ki dilute hydrochloric, nitric, and acetic acids and is also soluble ki ammonium nitrate and ammonium chloride solutions. 

A pliotornicrograpli of barium carbonate fomied by precipitation using pure soda asli (eq. 9), is shown in Figure 3. Tire av erage particle size is 1.2 ]lm. Tire exclusive use of soda ash results in a barium carbonate having included sodium that cannot be reduced below a certain level by repeated washings. Tire sodium can be detrimental if the BaCO is to be used for barium titanate production. 

Supply and Demand. Hie barium carbonate supply and demand in the United States for the years 1985 through 1989 is given in Table 4. 

Table 4. United States Barium Carbonate Supply and Demand, t...

Uses. Hiere are several different grades of barium carbonate manufactured to fit the specific needs of a wide variety of applications very fine, highly reactive grades are made for the chemical industry coarser and more readily haridleable grades are mainly supplied to the glass industry ... 

In 1989, 30% of the barium carbonate produced was used in glass manufacturing, 30% in brick and clay products, 20% in the manufacture of barium chemicals, 5% in the manufacture of barium ferrites, 5% in the production of photograpliic papers, and 10% in miscellaneous uses. 

Glass-grade barium carbonate has a high bulk density so that it does not become airborne when charged to the furnace. It also has a particle size... 

Barium carbonate prevents formation of scum and efflorescence in brick, tile, masonry cement, terra cotta, and sewer pipe by insolubilizing the soluble sulfates contained in many of the otherwise unsuitable clays. At the same time, it aids other deflocculants by precipitating calcium and magnesium as the carbonates. This reaction is relatively slow and normally requites several days to mature even when very fine powder is used. Consequentiy, often a barium carbonate emulsion in water is prepared with carbonic acid to further increase the solubiUty and speed the reaction. 

In the oil-weU drilling industry, the barite suspension used as drilling mud can be destabilized by the presence of soluble materials such as gypsum. Addition of barium carbonate precipitates the gypsum, inhibits coagulation, and thus permits the mud to retain the desired consistency and dispersion. 

Barium carbonate of finely controlled particle size reacts in the soHd state when heated with iron oxide to form barium ferrites. Magnetically aligned barium ferrite [11138-11-7] powder can be pressed and sintered into a hard-core permanent magnet which is used in many types of small motors. Alternatively, ground up magnetic powder can be compounded into plastic strips which are used in a variety of appHances as part of the closure mechanism. 

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