Computer studies of the composition of Chilean nitrate ores: Data reduction, basic statistics and correlation analysis

Abstract

Electronic computer studies were made on a suite of 815 chemical analyses of soluble salines in nitrate ores, representing monthly averages of ores treated by the two largest nitrate plants in Chile from 1932 to 1967. A package statistical program, STATPAC, of the U.S. Geological Survey was utilized: 1) to estimate the abundance of sodium not reported in the analyses, 2) to determine the soluble-insoluble ratio, 3) to calculate the basic statistics, and4) to investigate the correlation between the saline constituents. The statistical average composition of the soluble salines in these nitrate ores, estimated to be a close approximation of the average of Chilean ores as a whole, is as follows (in weight percent; the standard deviation is given in parenthesis): NO 3 6.29(+0.60), CZ 4.58(+1.26), SO 4 10(+3.16), IO 3 0.060(+0.012), CZO 4 0.028(+0.012), B 5 0 9 0.50(+0.11), Na 6.90(+1.19), K 0.73(+0.36), Ca 1.81(+0.55), Mg 0.46(+0.28), percentage of solubles 31.36(+5.69). The analyses do not give the true abundance of salines of low solubility such as anhydrite, which commonly makes up several percent of the nitrate ore, nor of several other saline ions occurring in minor or trace amounts which together generally do not make up more than a percent or two. Tables are presented for the significant correlations between relative abundances of the constituents, which give a clue to the mineralogical composition of the nitrate ore. However, the analysis of these correlation studies has not yet been completed.