ANSI AWWA B202-19 pdf free download – Quicklime and Hydrated Lime
Some water utility personnel still believe that a better evaluation of lime can be made and that more accurate results can be obtained by determining total CaO. In addition to available CaO, such an analysis determines CaO present as calcium carbonate—a factor of little importance in water treatment. For those who prefer the total CaO method, and for those who wish to make a complete analysis, the methods outlined in ASTM * C25, Standard Test Methods for Chemical Analysis of Limestone, Quicklime, and Hydrated Lime, are recommended. The amount of available CaO varies in limes from different geographic regions. Factors such as source of rock, manufacturing conditions, type of kiln, type of fuel, and even personnel have an effect on product quality.
Lime. A lime that slakes at a rate consistent with plant equipment is more economical to use and less difficult to handle. A slaking-rate test to determine the reactivity of lime is included in this standard. This procedure was devised to control the variables that occur in the test, thus improving the reproducibility of results. The results of the slaking-rate test on a given quicklime should be correlated with the performance of the lime in the slaker. The slaking requirement for the lime can then be specified. Because most modern lime-slaking equipment contains devices for the removal of grit, sand, pebbles, and other coarse inert material and because overloading of the grit- removing devices is undesirable, a test for insoluble matter is provided in this standard.
Magnesium and Insoluble Material. This standard sets no limit on magnesium because keeping the available CaO content within the specified limit should address any excess magnesium problem adequately. No provision is made for high-magnesium lime for the specific reason that such lime is not suited for water treatment. Although insoluble matter (iron and aluminum) can cause turbidity when lime is applied to filtered water or to a water supply not to be filtered, no limit is set for these constituents because turbidity problems can be overcome by adding the lime as a saturated solution. If such a procedure is impractical, individual treatment plants may need to set up limits for total insoluble matter, iron, and aluminum when purchasing lime. This condition occurs so rarely that a provision for it in this standard is unwarranted. The test for insolubles included in this standard determines only those insolubles that are coarse enough to be retained in the slaker or grit remover. Likewise
Size and Marking. Sizes of lime are established in the standard to meet the requirements of various types of feed equipment. Alternatively, purchasers may set size requirements to meet specific conditions. A change in size requirements should be made only after consultation with the manufacturer of the feed equipment being used. The standard also does not require the date of manufacture to be stamped on the bags in which the hydrated lime is shipped; it is assumed that the material will be delivered to the point of use in a condition to be handled readily in a dry-feed machine.