Content Variations of Rubidium and Bromide in Sylvite Derived from Carnallite by Leaching of Magnesium Chloride

The relationship between sylvinite and carnallite is important in the potash mine body contained carnallite,especially sylvinite overlies carnallite,the reverse of a normal depositional sequence.Trace elements are more

Potassium recovery from muscovite using NaCl-roasting followed by H_(2)SO_(4)-leaching

The present study aims at the recovery of potassium from muscovite mica(which contains K_(2)O;~10 wt%)using NaCl-roasting coupled with H_(2)SO_(4)-leaching process.The preliminary acid leaching studies applying different mineral acids resulted in a potassium recovery of 8%−18%.The optimum leaching conditions for the maximum recovery were 4 mol/L H_(2)SO_(4),60 min leaching time and liquid-solid ratio 4 mL/g at 90℃.However,the roasting of muscovite with additive NaCl(muscovite:NaCl mass ratio of 1:1.00,900℃,45 min)followed by H_(2)SO_(4)-leaching(95℃,60 min)extracted potassium to the tune of 98%.Under similar roasting conditions,the H_(2)O-leaching process extracted only 60%of potassium.The effects of various roasting and leaching parameters such as temperature,time,NaCl concentration,acid concentration,liquid-solid ratio on potassium extraction were evaluated.The appearance of the sylvite(KCl)mineral phase in the NaCl-roasted muscovite and its disappearance in the acid/water leached residue confirmed the physical and chemical distortions of the muscovite crystal structure.The possible mechanism of potassium release from the complex muscovite structure was elucidated based on available literature substantiated by characterizations using X-ray diffraction(XRD)and scanning electron microscopy with energy dispersive X-rays spectroscopy(SEM-EDX).

Palynology and stratigraphy of the thick evaporate-bearing Shashi Formation in Jiangling Depression,Jianghan Basin of South China,and its paleoclimate change

In the greater inland Jianghan Basin of South China,three salt depressions are lacking accurate geological times,of which Jiangling Depression is the largest.Evaporites are important records of paleoclimate,however,the geological ages of evaporates are very difficult to be determined because often evaporates have scare macrofossils and microfossils.Nonmarine Cretaceous to Tertiary halite deposits interbedded with mudstones are widely distributed in China.Paleocene-Eocene Thermal Maximum had very high temperatures and attracted strong interests of geologists because these times can be compared with future climate change because of global warming.However,previous studies focused on marine sediments found that during the Paleocene-Early Eocene,massive evaporate deposits formed in Jiangling depression of the Jianghan Basin.In this paper,the authors show that the Shashi Formation halite deposits formed in the Paleocene according to palynology.Most of these palynology fossils are arid types,so the massive evaporites in the Jiangling depression could be closely related to the hot Paleocene climate.High temperatures during the Paleocene contributed to the formation of the massive evaporates in the Jiangling Depression,until sylvite was the result.