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Bledug Kuwu, Grobogan, Central Java is rich in salts in the form of Na+, K+, Ca2+, Mg2+. This natural potential can be used as an alternative material for making potassium fertilizer needed for plants. This research tries to extract potassium from Kuwu Bledug mud using a process of aquadest leaching, partial evaporation and selective dissolution. The stages of the study were as follows: Kuwu bledug mud was leached using aquadest at a ratio (g/ml) of 1: 2, a temperature of 40 °C, stirring speed of 200 rpm for 4 hours. The process was followed by partial evaporation up to 50% by volume and chemical precipitation using chemical reagents such as limestone and CaSO4 which was varied by 2, 4, 6 grams at 60 oC for 60 minutes. The results showed that the Bledug Kuwu mud could be used as a source of potassium fertilizer as had a potassium content of 58.08 ppm. Potassium levels increased to 220.52 ppm by partial evaporation. Potassium levels were reduced from 220.52 to 123.23 ppm with the addition of limestone. This indicates potassium precipitated into a solid K2O. Potassium levels increased from 123.23 to 589.14 ppm with the addition of 2 grams of CaSO4. [ABSTRACT FROM AUTHOR]

The demand of high purity quartz sand is increasing for various needs such as solar cells, semiconductor chips, optical fibers, catalytic chemicals, and flat panel displays. One of the most widely used processes for this purpose is the one step or two step leaching method. This study investigated purification process to increase the silica content of quartz sand using the one step leaching method using dilute hydrochloric acid and comparing to two step leaching using dilute hydrochloric acid and sodium bicarbonate as solvent. The effectiveness of the process of removing impurities from quartz sand was studied based on the results of analysis using XRF, XRD, and SEM-EDX. The results showed that two step leaching with dilute HCl and Na2CO3 was effective in reducing the level of impurities in quartz sand after the one step leaching using very low concentrations of hydrochloric acid. Dilute Na2CO3 can improve impurities removal. SiO2 concentration increased from 96.3% in raw material to 98.3 and 98.8% after one-step and two-step leaching, respectively. Effectiveness of removing impurities increased from 54% by one step leaching method to 67.6% by two step leaching method. [ABSTRACT FROM AUTHOR]

Currently, due to the decreasing availability of sulfide ores, laterite ores are attracting much attention as nickel reserves. Laterite ore with nickel content of 1.35% can not be processed in Indonesia, therefore it is necessary to do processing in order to increase the laterite ore grade. One of nickel laterite processing is leaching in sulfuric acid solution. To produce a product with high levels of the metal nickel-metal impurities that come dissolved, particularly iron must be removed first from the results of the leaching solution. After separating the iron, nickel is deposited so that an intermediate product is produced in the form of Mixed Hydroxide Precipitate. The experiment was started by leaching using 1 M H2SO4 solvent, leaching time 6 hours, S/L 10 g/100 ml, stirring speed 400 rpm, variations in the addition of hydrogen peroxide 3, 5, 7, and 9 ml, and variations in temperature 30, 50, 70, and 90°C. The leached solution was then separated from the iron in 2 stages, namely the first stage with the addition of 25 wt.%/wt.% CaCO3 at a temperature of 90°C, a time of 2 hours, and a pH of 4.25. Then the second stage was with the addition of CaCO3 12.5 w/w with a temperature of 70°C, time of 1 hour, and pH 7. After that, nickel was deposited using MgO 20% wt.%/wt.% at a temperature of 50°C, 1 hour, and pH 9. The results showed that the highest extraction percent was achieved in 1 M H2SO4 conditions, leaching time of 6 hours, S/L 10 g/100 ml, stirring speed of 400 rpm, the addition of 9 ml of hydrogen peroxide and a temperature of 90°C is equal to 94.47%. [ABSTRACT FROM AUTHOR]