Lime precipitation

Recovery from Brines. Natural lithium brines are predominately chloride brines varying widely in composition. The economical recovery of lithium from such sources depends not only on the lithium content but on the concentration of interfering ions, especially calcium and magnesium. If the magnesium content is low, its removal by lime precipitation is feasible. Location and avadabiHty of solar evaporation (qv) are also important factors. 

Alkalinity Reduction. Treatment by lime precipitation reduces alkalinity. However, if the raw water alkalinity exceeds the total hardness, sodium bicarbonate alkalinity is present. In such cases, it is usually necessary to reduce treated water alkalinity in order to reduce condensate system corrosion or permit increased cycles of concentration. 

Rotary vertical shaft turbine units as shown in Figure 10 and other rotary or reciprocating equipment are other examples. Tapered flocculation may be obtained by varying reel or paddle size on horizontal common shaft units or by varying speed on units with separate shafts and drives. In applications other than coagulation with alum or iron salts, flocculation parameters may be quite different. Lime precipitates are granular and benefit little from prolonged flocculation. 

In the North American market, water heaters are almost always made with the cold water inlet and hot water outlet lines coming out of the top of the tank. The hot water outlet opens right into the top of the tank and so draws off the hottest water. The hot water has risen to the top of the tank because of its lower density. The cold water on the inlet side is directed to the bottom of the tank by a plastic dip-tube. In some models the dip-tube is curved or bent at the end to increase the turbulence at the bottom of the tank. This is to keep any sediment from settling on the bottom of the tank. As sediment— usually calcium carbonate or lime—precipitated out of the water by the increased temperature builds up, it will increase the thermal stress on the bottom of a gas-fired water heater and increase the likelihood of tank failure. On electric water heaters the sediment builds up on the surface of the elements, especially if the elements are high-density elements. Low-density elements spread the same amount of power over a larger surface of the element so the temperatures are not as high and lime doesn t build up as quickly. If the lower elements get completely buried in the sediment, the element will likely overheat and burn out. 

Supply of MU water for a medium-pressure (450 psig) WT boiler, from a surface water source with very variable suspended solids and hardness (sugar refinery, South Africa). The process used is a. carbonate removal using hot-lime precipitation softening coupled with silica adsorption by magnesia addition b. clarification in anthracite filters and c. cation ion-exchange for the balance of hardness removal. 

The conventional technique for removing zinc from the spinning acid wastestream has been direct lime precipitation to -pH 10, with no zinc recovery. The economics of this approach are compared to the American Enka zinc recycle process. 

A very limited amount of individual plant specific data for the aluminum forming industry is available. Data available on the influent and effluent streams are discussed briefly in the following subsections for specific plants. This aluminum processing plant uses lime precipitation (pH adjustment) followed by coagulant addition and sedimentation as its treatment system. Data... 

Removal of Pollutants by Lime Precipitation at Metal Processing Plant Aa... 

Removal of Pollutants by a Combination of Lime Precipitation, Sedimentation, and Filtration at Plant Ba... 

Removal of Heavy Metals from Coil Coating Wastewater by Lime Precipitation, Clarification, and Filtration... 

The process flow scheme consists of chromium reduction, lime precipitation, and clarification. 

The recommended treatment option for control of toxic pollutants regulated under PSES categorical standards is chemical substitution. Although chemical substitution of sodium hydrosulfite for zinc hydrosulfite is recommended for control of zinc at groundwood mills, PSES for zinc were calculated using treatment performance data for lime precipitation.39... 

In about 1865 he found that some of the copper veins of the Lower Keuper Sandstone of the Trias in Cheshire contained vanadium (37) and that one of the lime precipitates from this ore contained about two per cent of it. It was from this unpromising material that Roscoe and Sir Edward Thorpe laboriously prepared the pure vanadium compounds needed for a thorough study of the element. 

Sodium hydroxide has been examined as a substitute for lime (USEPA 1986). Sodium hydroxide precipitation agents have been shown to generate 12% less dry solids than lime precipitation. 

Bhattacharyya, D.C., Sund-Hagelberg, K. Schwitzgebel, G.M. Blythe, and F.B. Craig, (1980), "Removal of Heavy Metals, Arsenic, and Fluoride from Smelter Effluents by Sul fide-Lime Precipitation," Proceedings of the Industrial Wastes Symposia, Las Vegas, N.V. 

The addition of lime to control acid drainage from mining wastes typically produces calcium arsenates (Pichler, Hendry and Hall, 2001). Bothe and Brown (1999) further concluded that lime precipitates As(V) as a number of hydroxyl and hydrated calcium arsenates (Ca4(OH)2(AsC>4)2 4H2O, CaslAsCLLOH (arsenate apatite), and/or Ca3(AsC>4)2 3H2O) rather than anhydrous tricalcium orthoarsenate (Ca3(As04)2). Calcium arsenates also occur in coal combustion byproducts (Chapter 7). In the flue gas treatment systems of coal combustion facilities, volatile arsenic can readily react with calcium to form the arsenates on the surfaces of flyash and injected lime (Seames and Wendt, 2000 Yudovich and Ketris, 2005, 175). 

Only a few samples were taken from the alleged homicidal gas chambers. Care was taken to ensure that samples were only taken from material not exposed to weathering. Only a few places in morgue 1 (the alleged gas chamber ) in crematorium II at Birkenau, where a pillar supports the roof even today and has therefore visibly protected both the underside of the roof and parts of the wall from all influence of weathering, exemplified by the deposition of spider webs many years old and the absence of any trace of lime precipitation on the concrete or mortar, which would be caused by rain water. 

Schmidt RL, Joyce TW. An enzymatic pretreatment to enhance the lime precipitability of pulp mill effluents. Tappi 1980 63(12) 63-67. 

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