Document jy3N7qEr6b3ZxMEo8p1ykoEB9

GYPSUH PRODUCTS KAFUAL Chapter 7 CRUSH1"D ROCK FOR PORTLAND CLIENT MANUFACTURE Tremendous quantities of crushed gypsum rock are used to retard the setting time of Portland Cement. From l.$% to 6.55 gypsum is usually added to the cement clinkor arid the mixture is then ground up together to a fine inti mately mixed powder. According to standard specifications, Portland Cement cannot contain more than 3.0% sulphur trioxide (SO3) and as the amount added is carefully regulated, most cement producers purchase gypsum rock on speci fications as to the siso of the rock and the percent SO in the rock. Ordinarily two sizes of crushed fypsnm rock are furnished; (a) ungraded in which all the rock will pass a lj" screen including all lines and; (b) graded in which all passes a 1-|" screen and is retained on a or a screen, thus eliminating most of the fines. Specifications for sizes other than these should be first referred to the Manufacturing Department to sec if it can be supplied. IQOfc pure gypsum contains U6.55 SO3. As no gypsum rock deposit is 100% pux-e , SesTwall guarantees^ the followin;j`"ercenta-es of SO 3 at our~various mills as follows: Acme, Texas Average Analysis U5.6% S03 -- 77.55 Blue Ranids, Kansas Sigurd, Utah II it R6.05 It -- 78.25 tr u Usiy> 11 -- 76.7/^ (Crushed rock (for retarder) is not available at Ft. Podge, Grand Rapids or Akron, October 1958) Most complaints on crushed rock are on low SO3 content; or too large a percent of fines in graded rock: or on wet rock. A complaint on low SQ^ almost always is found to be unjustified and is caused usually by improper or careless sampling oi the shipment. A grab sample is not representative' and the sampling muse be done according to the we 11-recognized procedure of collecting a several hundred pound sample taken from all parts of the car, grinding and quartering down this sample so that the powde'r taken for analysis is representative of the entire car. Gypsum is one of the softest minerals found in nature and is easily abraided and broken so that in the process of screening, loading and unloading some fines are formed, so that in a graded rock some fines that will pass the smaller screen will bo formed. However, this amount should not exceed 155 by weight. The free iratcr in the rock from our mines will not exceed 15 and in most cases will not exceed 0.55. Complaints on too much water in the rock are usually due to leaky box cars or uncovered gondolas and are not due to the presence of excess water in the rock as it comes from, the mine. 5.020 November 1, 19.58 SGP 0003356 CffPSUK PRODUCTS hkNUnh Chapter V Another complaint that arises is presence of anhydrite. As noted, gypsum is normally a soft material. Anhydrite is very hard. This presents -problems in grinding. Also, anhydrite has no whter of crystallisation land so ,-fives a higher SO. content per ton. If not accounted for, the Portland Cement manufacturer runs into problems due to varying SO3 content. Bestwall gypsum deposits noted have no anhydrite traces. Basically, anhydrite is avoided even in processing gypsum. There is some interest in the use of poire anhydrite in the manufacture of special Portland Cements. Bestwall is not in a position to ship straight anhydrite in carload quantities. 5-02] ,1 1?58 SGP 0003357 Chapter V AGRICULTURAL JYFSUIl Rock gypsum ground to a powder is commonly known asl!land plaster" especially in its use as a fertilizer for the so-called leguminous crops which consist of clover, alfalfa, peas, beans, peanuts, etc, land Plaster is a valuable plant food for such crops as it supplies sulphur and frees magnesia and potash for plant foods. It also increases the growth of the bacteria which transform available nitrogen into plant food. Hundreds of cars arc used annually for fertilizing peanut crons in the Southern States. Land Plaster added to manure unites with nitrogen forming ammonium sulphate, a stable compound valuable as a plant food. A great deal is sold in the Western States also. A use in recent years has been as a treatment in ponds to clear the water. 600 pounds per acre per foot of depth after the spring rains will clear a bods'- of' water and improve it for the full summer. ilany states have Fertiliser Laws requiring a license and/or a foe to sell such a product as Agricultural Gypsum. In 1?5S B^stwall had a license to sell Agricultural Gypsum in Oregon, Idaho, '-vashington and Utah. Schedule 3, page 3A contains a note listing states whore Agricultural Qypsum may be sold 'without a license. Consult the General Sales Office for further information on where Scstwall has a license to sc.11 Agricultural ftypsvm or does not need one. When' sold as "Ground Gypsum" no license is required. Scstwall Agricultural Gypsum, or Lcstwall "Ground Gypsum", is available at Acne, Akron, Biu. Rapids, Ft. Dodge, Grand Raoids and Sigurd. The characteristics of this material for each is: Agricultural Gypsum Ground Gypsum Acme Akron BlwRapa. iPt.Dodge -Gr.Rapy. .Sigurd Average Purity Gypsum Average S0-> Content rj " /'> Grind % Retained 100 200 Inspection 5.022 November 1, 1956 SGP 0003358