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Sodium bisulfate is a weaker form of sulfuric acid and as such is useful in lowering <br /> the pH when only minor adjustments are required. The chemical is supplied as a dry <br /> powder and would be fed to the system as diluted solution containing approximately <br /> 10 to 20 percent dissolved chemical. <br /> Scale Control <br /> Scale deposits and sludges that accumulate in boilers are due mainly to hardness, <br /> silica and corrosion products. Most of the control will be provided by the softening <br /> and RO demineralization of the boiler makeup water and boiler blowdown. However, <br /> it is anticipated that residual amounts of the scale constituents will buildup and <br /> require the addition of small amounts of control chemical. There is a selection of <br /> several sodium phosphate chemicals that can be used for scale control that function <br /> by reacting with calcium to precipitate insoluble hydroxyapatite which tends to not <br /> stick to the boiler wetted surfaces. The more common phosphates include: <br /> monosodium phosphate, disodium phosphate and trisodium phosphate. All of these <br /> chemicals can be supplied as dry powders and would be injected into the steam <br /> drum of the boiler at the required dilution. <br /> To prevent corrosion in the pipelines that return condensate to the boiler, a group of <br /> chemicals called amines are generally added directly into the steam lines. The most <br /> probable choice of an amine would be the compound morpholine or <br /> cyclohexylamine. Like the phosphate chemicals, an amine would be added at an <br /> appropriate concentration to control pipeline corrosion. <br /> C. COOLING TOWER WATER TREATMENT <br /> Softening of the makeup water to the cooling water system and operating within a <br /> reasonable range of concentration in the recirculating tower water will reduce the <br /> need for scale control chemicals in AmerAlia's pilot plant. The chemical treatments <br /> that maybe required include pH, scale control and microbial control. <br /> If the alkalinity in the cooling tower circulating water becomes too high, sulfuric acid <br /> will be used to lower the pH by additions to the tower sump. Also, sulfuric acid will <br /> keep the common scale-forming minerals (such as calcium carbonate) dissolved. <br /> Cooling water systems provide a favorable environment for microorganisms to grow. <br /> Depending upon the physical and chemical conditions of the water various kinds of <br /> G:\LMW\78545.002\Reclamation\Reclamexh.DOC D-45 <br />