Gypsum Analysis

REFERENCE Green. G. W.. Gypsum Analysis with the Polariring Micro8co re, The Chemistry and Technology of Gypsum. ASTM STP 861. R. A. Kuntze. Ed.. American Society for Testing and Materials. 1984, pp. 22-47. 

C471-91 Chemical Analysis of Gypsum and Gypsum Products ... 

Because of the large difference in the behavior of the thin plywood and the gypsum board, the type of interior finish was the dominant factor in the statistical analysis of the total heat release data (Table III). Linear regression of the data sets for 5, 10, and 15 min resulted in squares of the correlation coefficients R = 0.88 to 0.91 with the type of interior finish as the sole variable. For the plywood, the average total heat release was 172, 292, and 425 MJ at 5, 10, and 15 min, respectively. For the gypsum board, the average total heat release was 25, 27, and 29 MJ at 5, 10, and 15 min, respectively. 

Loeppert RH, Suarez DL. Carbonate and gypsum. In Bartels JM (ed.), Methods of Soil Analysis Part 3 Chemical Methods. Madison, WI Soil Science Society of America and American Society of Agronomy 1996, pp. 437-474. 

Gypsum Saturation from Measurements of Dissolved SOg. Use of measurements of dissolved calcium to determine gypsum saturation is relatively easy from a computational standpoint use of measurements of dissolved SO2 is more difficult. However, wet chemical analyses for calcium are frequently subject to interference by high concentrations of magnesium. For installations where a quick and reliable analysis for calcium is not available, the use of dissolved SO2 is preferred, and the following correlation applies ... 

Recognizing the need for a more economically and environmentally friendly citric acid recovery process, an adsorptive separation process to recover citric acid from fermentation broth was developed by UOP [9-14] using resin adsorbents. No waste gypsum is generated with the adsorption technique. The citric acid product recovered from the Sorbex pilot plant either met or exceeded all specifications, including that for readily carbonizable substances. An analysis of the citric acid product generated from a commercially prepared fermentation broth is shown in Table 6.2, along with typical production specifications. The example sited here is not related to zeolite separation. It is intent to demonstrate the impact of adsorption to other separation processes. 

XRD allows the determination of the actual mineral species present. The bulk coal samples resulted in an x-ray pattern with a high background due to the coal matrix. The major mineral species were easily determined, however the minor species could not be detected. As with the SEM-BSE analysis, interpretation of results in a quantitative manner (in relation to the coal) is difficult. The major minerals detected were quartz, kaolinite, gypsum and marcasite. 

To determine the rate of dissolution of hemlhydrate crystals, the same vessel was used as for the crystallization study. The vessel was filled with the sulphate-rich solution (zero Initial calcium concentration). An amount of sieved hemlhydrate seed crystals, about 10% In excess of that required to saturate the solution, was added. At very short time Intervals, samples were taken using a similar procedure to that for the gypsum growth Investigation. Samples were separated Into crystals for size analysis (with a 190pm orifice) and crystal content and solutions for analysis. Further details are given by Mukhopadhyay (17). 

As far as the gypsum crystals are concerned, the analysis is identical to that for a seeded MSMPR (34). The information required is the growth rate and the mean residence time. For the hemihydrate, the analysis is that for a continuous seeded MSMPR dissolver (35), which parallels that for the crystallizer. The information needed is the dissolution rate and the mean residence time. 

Chemically pure reagents were used. Cadmium was added as its sulfate salt in concentrations of about 50 ppm. Lanthanides were added as nitrates. For the experiments with other metal ions so-called "black acid from a Nissan-H process was used. In this acid a large number of metal ions were present. To achieve calcium sulfate precipitation two solutions, one consisting of calcium phosphate in phosphoric acid and the other of a phosphoric acid/sulfuric acid mixture, were fed simultaneously in the 1 liter MSMPR crystallizer. The power input by the turbine stirrer was 1 kW/m. The solid content was about 10%. Each experiment was conducted for at least 8 residence times to obtain a steady state. During the experiments lic iid and solid samples were taken for analysis by ICP (Inductively Coupled Plasma spectrometry, based on atomic emission) and/or INAA (Instrumental Neutron Activation Analysis). The solid samples were washed with saturated gypsum solution (3x) and with acetone (3x), and subsequently dried at 30 C. The details of the continuous crystallization experiments are given in ref. [5]. 

At this point, Lavoisier was primarily interested in doing research that would impress the academicians. He read his first paper to the Academy as a visiting scientist (that is, a non-member) on February 27,1765. It dealt with a topic that had been pursued by some of the chemists in the Academy and was titled The Analysis of Gypsum. Gypsum was the mineral from which plaster was made, so it was a topic with practical applications. The two referees appointed by the Academy to judge the paper reported favorably on it and recommended it for inclusion in the Academy s Savants etrangers collection. It is probable that some sort of behind-the-scenes deal had been made because both referees were friends of Lavoisier s father. 

Potassium sulfate is used in fertilizers as a source of potassium and sulfur, both of which are essential elements for plant growth. Either in simple form or as a double salt with magnesium sulfate, potassium sulfate is one of the most widely consumed potassium salts in agricultural apphcations. It is preferred over potassium chloride for certain types of crops such as, tobacco, citrus, and other chloride—sensitive crops. Some other applications include making gypsum cements to make potassium alum in the analysis of Kjeldahl nitrogen and in medicine. 

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