Method for preparing potassium dihydrogen phosphate solution and coproducing special fertilizer for sweet potatoes

Abstract

The invention belongs to the technical field of chemical engineering and particularly relates to a method for preparing potassium dihydrogen phosphate solution and coproducing a special fertilizer for sweet potatoes. By changing the temperature and other coefficients of the potassium dihydrogen phosphate solution which is prepared from phosphoric acid by adopting a wet process, the purity of the potassium dihydrogen phosphate solution can be improved, and meanwhile, a combined compound fertilizer containing N, P and K can be produced. In addition, by adding formaldehyde into a filtrate to prepare the controlled-release compound fertilizer and improving the purity of the potassium dihydrogen phosphate solution, the produced special fertilizer for sweet potatoes has good absorption rate and can meet the needs of sweet potatoes for nutrients in each period of the growth cycle and increase the yield of sweet potatoes. The special fertilizer is a high-efficient compound fertilizer.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a production method for preparing a special fertilizer for sweet potato by-product of a potassium dihydrogen phosphate solution. Background technique [0002] Potassium dihydrogen phosphate solution is widely used in almost all types of crops such as various types of economic crops, grain, melons and fruits, vegetables, etc. It has many excellent functions such as significantly increasing production and income, improving quality and quality, resisting lodging, resisting diseases and insect pests, and preventing premature aging. , and has the effect of overcoming the nutrient deficiency caused by the aging and absorption capacity of the root system in the later stage of crop growth. At present, many domestic fertilizer manufacturers are producing potassium dihydroxide phosphate solution compound fertilizer. The production methods mainly include neutralization method, ext...

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Problems solved by technology

Traditional fertilization of sweet potatoes all uses poultry manure, such as the invention patent of CN201310506237.2 "a kind of sweet potato dregs chicken manure fertilizer and its preparation method" and the invention patent of CN201210566294.5, which uses sweet potato dregs to prepare chicken manure. The main raw material of the method for manure is exactly sweet potato slag and chicken manure, and its main defect is: N, P, K in poultry manure can't be determined, and the output of sweet potato can't be kept in a good scope; And use fertilizers such as plant ash, For example, the invention patent of CN201210142052.3 "a formula fertilizer for high-yielding sweet potato", the main raw materials are jujube wood, apricot wood, peach wood, and miscellaneous wood are calcined into ash respectively. The advantage is that the content of P and K High, but the content of N is low. In the early stage of sweet potato growth, it is impossible to close the forest quickly. In some arid areas, the closed forest time is too long, and the soil water loss is fast, which will cause low yield of sweet potato; there are also nitrogen, phosphorus, Potassium mixed fertilizer, such as the invention patent of CN200910227408.1 "a kind of formula fertilizer for sweet potato", its main components are carbonamide, superphosphate, calcium magnesium phosphorus and potassium chloride, and its disadvantage is that the mixed fertilizer Poor absorption, reportedly:

[0012] The unabsorbed mixed fertilizer is easy to cause soil compaction. At the same time, the release and loss of the fertilizer is too fast, which will cause the sweet potato vines to grow wildly in the early stage. In the later stage, due to the crazy growth of sweet potato and the soaking of rainwater or the decomposition of the fertilizer itself, the nutrients in the soil cannot be supplied to the sweet potato. needs, resulting in extremely low output

[0013] In the process of producing potassium dihydroxide phosphate solution for wet-process phosphoric acid, the purity of potassium dihydroxide phosphate solution is not high, and the filtrate also contains a large amount of unprecipitated carbonamide, K + 、H 2 PO 4 - 、HPO 4 2- 、PO 4 3- and other substances, the researchers of the present invention have studied the composition content of traditional sweet potato special fertilizer and the absorption situation of sweet potato from a large amount of prior art documents and many years of exploration and research, and have effectively explored the production of phosphoric acid diphosphate from wet-process phosphoric acid. The special fertilizer for sweet potato is prepared from the filtrate of potassium hydroxide solution to solve the problem that the active ingredients in the filtrate of potassium dihydrogen phosphate solution produced by wet-process phosphoric acid cannot be used. There is no report in domestic fertilizer production.

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