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Leaching with Acids
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2019
Phosphate rock is acidulated with sulfuric acid in the manufacture of superphosphate and phosphoric acid. These technologies are too well known to warrant any elaboration. However, from the metallurgical point of view, phosphate rock is an important potential source for uranium, since sedimentary phosphate rock usually contains on the average 150 ppm uranium. When considering the world production of phosphates of 110 × 166 ton, the amount of uranium associated with this material would be 16,500 ton. In the production of superphosphate, all the uranium originally present in the rock is contained in the product and is lost when the product is applied to the soil as a fertilizer. Phosphoric acid, on the other hand, also contains much of the uranium originally present in the rock in solution, and the scale of phosphoric acid operations today and the current price of uranium are beginning to make the recovery of uranium from phosphoric acid a worthwhile proposition. The techniques employed, however, are based on solvent extraction and do not include further use of sulfuric acid.
The Chemistry of Hazardous Materials
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
Sulfuric acid, once known as the oil of vitriol, is the least expensive of the commercially prepared acids and can be prepared and shipped in pure form. It is used by the fertilizer industry to convert insoluble phosphate rock into soluble superphosphate, which supplies phosphate ions required by growing plants. Sulfuric acid is also used as the electrolytic solution in automobile batteries, as well as in metal treatment known as a “pickling process.” Pickling here means dipping the metal part in a bath of sulfuric acid to remove rust and other contaminants.
Mining
Published in Howard T. Odum, Elisabeth C. Odum, Mark T. Brown, Environment and Society in Florida, 2018
Howard T. Odum, Elisabeth C. Odum, Mark T. Brown
These phosphate deposits are now being commercially mined (Figure 25.2). Drag lines remove the soil, upper sediments, and rocks (called overburden), putting them in temporary piles. The phosphate rocks and sediments are lifted out and the associated clays washed off and stored in giant slime ponds. The slimes settle gradually as wetland vegetation invades. Eventually they dry out, becoming suitable for farms, forests, or settlements. Most of the overburden can go back into the mined cavities, the ground smoothed over, and vegetation replaced. The calcium phosphate may be used directly for fertilizer or processed to make superphosphate (H3PO4). Calcium phosphate is converted to superphosphate using sulfuric acid brought in from out of state. The sulfuric acid is combined with the apatite to yield superphosphate and gypsum. The chemical reaction is as follows: 3H2SO4+Ca(PO4)2→2H3PO4+3CaSO4(sulfuricacid)+(apatite)→(superphosphate)+(gypsum)
The potential ecological risk of soil trace metals following over five decades of agronomical practices in a semi-arid environment
Published in Chemistry and Ecology, 2018
Salar Rezapour, P. Kouhinezhad, A. Samadi
The study area, one of the most important agricultural areas of north-west of Iran, situated around the Piranshahr region (between latitudes 36° 43′ and 36° 51′ N and longitudes 45° 10′ to 45° 16′ E) in the western-Azarbayjan province (Figure 1). Geologically, the parent rock types mainly include (i) recent terraces and alluvial deposits associated with Quaternary age and (ii) limestone, sandstone, and shale formed in the mid-Cretaceous period [12]. The region typically has a semi-arid Mediterranean type of climate with a mean temperature of 12.5°C and an annual precipitation of 650 mm as both rainfall and snow [13]. The natural vegetation is grassland and shrubland that is modified, in places, by agricultural or industrial use. Most of the cultivated soils have been cropped by sugar beet, wheat, and pea and have irrigated with rainfall, ground water, or river water. For instance, agricultural inputs involving chemical fertilisers (mainly nitrogen and phosphate fertilisers), manures, pesticides, and tillage practices have been applied in the cropped soils. Agricultural practices are intensified with flood irrigation, ploughing into different depths to open up the hard soils, and fertiliser inputs irregularly, mainly manure, mineral N (as urea) and P (as di-ammonium phosphate and superphosphate). Chemical and organic fertilisers have been used at a level of about 250 kg ha−1 year−1 of urea, 150 kg ha−1 year−1 of superphosphate, and 30–60 ton ha−1 year−1 of manure. Farmers use largely, in addition, various agrochemicals to plant pests and fungi in the region.
Soil mineralogy-controlled phosphorus availability in soils mixed with phosphate fertiliser and biochar
Published in Environmental Technology, 2022
Stella Cristiani Gonçalves Matoso, Paulo Guilherme Salvador Wadt, Valdomiro Severino de Souza Júnior, Xosé Lois Otero Pérez
The biomasses (rice and coffee husks) were selected due to their high availability and worldwide distribution. The use of soil to compose enriched biochars proved to be effective in increasing the degree of aromaticity and thermal stability of biochars, while resulting in greater carbon retention during pyrolysis [21]. It is important to note that the soils used to compose the enriched biochars are not the same ones used in the experimental phase. The triple superphosphate is a typical phosphate fertiliser used as a source of P in agriculture.