Extraction and Reaction Mechanism of Potassium from Associated Phosphorus and Potassium Ore

Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigated, such as grinding fineness, the amount of sulfuric acid and fluoride salt, reaction time and temperature, etc. Meanwhile, the effects of various factors on the formation of soluble potassium and phosphate were also discussed. The reaction products and residues were determined by X-ray diffraction（XRD）, scanning electron microscopic（SEM） analysis and other means. The results showed that the dissolution rates of potassium and phosphorus were 70wt% and 93.7wt%, respectively, under the conditions of a grain size of 95.64wt% lessthan 0.074 mm, 9.78 g·g^（-1） sulfuric acid, 0.5 g·g^（-1） ammonium fluoride, 160 ℃ and a reaction time of 2h. The thermodynamic and chemical reaction mechanism was revealed that the primary reaction could be completed spontaneously in a temperature range of 298-433 K. The increase of reaction temperature had an important influence on ion exchange reaction, which was more conducive to the spontaneous process. The research will open up a new way for efficient use of potassium ore resources.

Nutrient Dynamics in Recycled Organic Amended Alkaline Soil

A variety of wastes are generated due to human activities. Organic waste usage in agriculture plays a significant role in the steady supply of plant nutrients through improving soil quality. An in vitro incubation study was conducted to measure the release of the major nutrients viz. available nitrogen (N), phosphorus (P), and potassium (K) in alkaline soil amended by recycled organic soil conditioners. The soil was amended by compost (Cm) and vermicompost (VC) @5 tha−1 and a mixture of compost and vermicompost (Cm + VC) @2.5 tha−1. Chemical fertilizers (Cf) were added @of 98.842 kg⋅ha−1 of urea and 64.99 kg⋅ha−1 of triple superphosphate (TSP), with amended soils being incubated for 120 days maintaining 50% field moisture holding capacity. Due to the sufficient content of potassium in experimental soil for plant growth, extra potassium was not added. Available soil N, P, and K were determined at every 0, 15, 30, 45, 60, 90, and 120 days of incubation. The highest available N and K release was found in VC treated soils at the incubation period of 45 days. On the other hand, the highest P release was recorded in Cm treated soils at the incubation period of 45 days. In this experiment, the addition of Cm, VC and Cm + VC showed better release of cumulative plant available N, P and K than either control (C) or Cf and were arranged as VC > Cm > Cm + VC > Cf > C, Cm > Cm + VC > VC > Cf > C and Cm + VC > VC > Cm > C > Cf for N, P and K, respectively. The results of this experiment revealed that the addition of compost and/or vermicompost is predominant over chemical fertilizer in supplying of major nutrients for crops in alkaline soil.