Sylvinite

Abstract: Brine from the saline Qarhan Lake was evaporated at 28±2°C in a clean environment. Two groups of experiments were conducted; one with complete separation of precipitate and brine at different stages of evaporation, and the other with continuous precipitation during the evaporation. Seventy-nine precipitate and brine samples were collected during the experiments, and the δ 37Cl values were determined using an improved thermal ionization mass spectrometry procedure for precise measurement of chlorine isotopes based on Cs2Cl+ ions. Based on the concentrations of Na+, K+, and Mg2+, evaporation was divided into three main precipitation stages as follows: halite dominant, carnallite dominant, and bischofite dominant. The δ 37Clsolid and δ 37Clliquid values of the precipitate and coexisting brine samples at different stages showed the following characteristics. The precipitates were enriched with 37Cl relative to the coexisting brine samples, and the δ 37Cl of both the precipitate and brine samples decreased gradually during evaporation. The fractionation factors (α h) between halite and brine were the highest, followed by that (α c) between carnallite and brine, and then that (α b) between bischofite and brine. The α c and α b values of less than one, which indicate the precipitate is enriched in 35Cl, were found when the evaporation process entered a new stage. However, the δ 37Cl values of carnallite, bischofite, and the coexisting brine samples decreased during evaporation. The residual brine is a 35Cl reservoir. The experimental phenomena were consistent with the δ 37Cl values in saline deposits in the literature. δ 37Cl can be used as an indicator of brine evaporation processes, which is important in the exploration of sylvinite deposits.

Abstract: Abrupt lateral and vertical changes from red carnallitite (carnallite-halite rock) to red sylvinite (sylvite-halite rock) occur in the Prairie Evaporite Formation between Watrous and Kandahar, Saskatchewan. Such changes are of considerable economic importance, since carnallite has undesirable physical properties and a relatively low content of potassium. The following four types of relationship between sylvinite and carnallitite are considered: (1) the rocks are facies equivalents deposited in different areas from essentially contemporaneous brines; (2) carnallite formed by reaction of sylvite with magnesium chloride brines; (3) sylvite derived from carnallite by leaching of magnesium chloride; (4) sylvite, as presently found, not directly related to carnallite, but formed through solution of pre-existing sylvite with subsequent crystallization. Sylvinite overlies carnallitite, the reverse of a normal depositional sequence. The distribution of traces of bromide and rubidium in the chloride minerals indicates that red sylvinite was formed by leaching of magnesium chloride from carnallitite. This conclusion is substantiated by textural observations at carnallite-sylvite contacts, where red sylvite has replaced carnallite and inherited iron-oxide inclusions from carnallite. A comparison of the proportions of carnallite and sylvite, in a given potash zone, from a region of carnallitite to an adjacent region of sylvinite, reveals that the amount of sylvite present corresponds to the amount which could be derived from carnallite by leaching of magnesium chloride. The potash zones are cumulatively about 50 ft thicker where they are red carnallitite than where they are red sylvinite. Since the total thickness of salts can be determined by seismic techniques, this provides a valuable prospecting guide to the presence of local areas of carnallitite. Not all the sylvite present is derived from red carnallite. A clear variety of sylvite, termed “clear sylvite,” can be distinguished from red sylvite by the absence of iron-oxide inclusions and by a relatively small rubidium content (0.003 weight percent). Petrographic evidence indicates that red carnallite locally has replaced clear sylvite. Seventeen potassium-argon dates on red sylvite range from Permian to Mississippian; two samples gave younger ages. These are minimum ages and the alterations of carnallite to sylvite may have been essentially contemporaneous with deposition.

Abstract: This invention relates to the concentrating, or separation of the values from soluble ores. More particularly, it relates to the separation of sylvite (potassium chloride-KC1) from a saturated solution of the soluble constituents of sylvinite ores such, for example, as those found in the Carlsbad...