BaSO

Qi L et al 1996 Preparation of BaSO, nanopartioles in non-ionio W/0 mioroemulsions Coll. Surf. 108 117... 

Some commonly encountered materials arranged in order of decreasing p. are lead > BaSO > bone > muscle > blood > liver > fat > air. 

Authigenic barium sulfate or barite [13462-86-7] is found in relatively high concentrations in sediments covering active diverging oceanic plate boundaries. It occurs as rounded masses containing up to 75% BaSO or as a dispersed constituent of the sediment. Its origins are uncertain, but it is likely that it is associated with hydrothermal actions. 

Barite, predominately BaSO, meets the overall requirements for weighting material better than other materials and is used for increasing the density of drilling fluids throughout the world. Commercial barite has a lower specific gravity than pure barium sulfate owing to the presence of associated minerals, such as silica. Barite is virtually insoluble in water and does not react with other mud constituents. Most operators prefer barite that meets API specifications (Table 2) (23). The barite content in mud depends on the desired density but can be as high as 2000 kg/km (700 lb/bbl). 

Llthopone. Lithopone is a mixture of ZnS and BaSO. The pigmentary properties of the mixture are deterrnined by 2inc sulfide and therefore Hthopone pigments are characteri2ed by the amount of ZnS present in the mixture. The amount of ZnS in commercial Hthopones varies from 15 to 60%. The most common is a 30% Hthopone pigment, containing 28—30% of ZnS and 70—72% of BaSO. ... 

The barium sulfide needed for the reaction is prepared by the reduction of barite [13462-86-7] BaSO, with petroleum coke in a rotary furnace ... 

Whiteness and Brightness. Photometric instmments, originally developed by the paper industry, are used for these measurements. Values are compared against standard white pigments such as BaSO, Ti02, or MgO. 

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. 

Ziac sulfate was made by 15 companies ia 1980 from secondary materials (93%) and from roasted ore, ie, ziac oxide (7%). The ziaciferous material reacts with sulfuric acid to form a solution, which is purified. After filtration, the solution is heated to evaporation and heptahydrate crystals are separated. It is sometimes sold ia this form but usually as the monohydrate [7446-19-7] which is made by dehydration at ca 100°C. Very pure ziac sulfate solution is made ia the manufacture of the pigment Hthopone [1345-05-7] ZnS-BaSO, and of ziac by electrowinning (see ZiNC AND ZINC ALLOYS). 

The basic aperture impedance method can produce three-part white cell differential counts. Impedance counters can distinguish three white cell types by size the LYMPHS, mid-range cells including MONOS and BASOS, and granulocytes including NEUTS and EOS. 

Pig. 4. (a), BASOS cytogram showing intensities for BASOS, mononuclear (MNs), and polymorphonuclear (PMNs) cells (b), intensity at SH, high angle... 

In its natural form, barium [7440-39-3] Ba, never occurs as the metal but is almost always found as the ore barite [13462-86-7] BaSO. More than 90% of all barium is actually used as the ore, albeit after preliminary beneftciation. The petroleum industry consumed 90% of the ore for oil- and gas-weU drilling duids (muds). The other 10% is used as filler and/or for extender uses and the manufacture of all other barium chemicals. Witherite, the only other significant natural barium ore, is not mined commercially (1). The quantity of U.S. barium chemicals produced in 1986 and 1987 is given in Table 1. 

Barite [13462-86-7], natural barium sulfate, BaSO, commonly known as barytes, and sometimes as heavy spar, tiU, or cawk, occurs in many geological environments in sedimentary, igneous, and metamorphic rocks. Commercial deposits are of three types vein and cavity filling deposits residual deposits and bedded deposits. Most commercial sources are replacement deposits in limestone, dolomitic sandstone, and shales, or residual deposits caused by differential weathering that result in lumps of barite enclosed in clay. Barite is widely distributed and has minable deposits in many countries. 

Thermal Reduction. Thermal reduction is usually accompHshed ki a high temperature countercurrent rotary kiln. "Hot zone," a region near the kiln spik, temperature is usually controlled at 1100—1200°C. The reaction rate has been shown to be only slighdy lower at 1050°C than at 1130°C (9). About 6% of the feed BaSO remains unreacted after 30 min at 1050°C. Reaction completion is approached ki less than 10 min at 1100°C (10). 

Reduction of BaSO appears to begin about 900°C (15). The presence of iron or iron oxide can cataly2e the barium (9) and also strontium reduction reaction rates. However, iron impurity can also increase the acid-soluble content of the black ash (9). 

Leaching is 90—95% complete as the soflds exit in the underflow of the first clarifier. Final washing of the soflds (mud) using fresh water takes place in a rotary filter from whence the mud, consisting of 65% H2O, 10—15% BaSO and siUcates, and 10—15% coke, is deflvered to landfill at an approved site. 

Barium sulfate [7727-43-7] BaSO, occurs as colorless rhombic crystals, mp 1580 °C (dec) sp gr 4.50 solubihty 0.000285 g/100 g H2O at 30°C and 0.00118 at 100°C. It is soluble in concentrated sulfuric acid, forming an acid sulfate dilution with water reprecipitates barium sulfate. Precipitated BaSO is known as blanc fixe, prepared from the reaction of aqueous solutions of barium sulfide and sodium sulfate. 

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