Synthesis of urea-formaldehyde controlled releasing fertilizer

Abstract

The synthesis process of urea-formaldehyde controlled releasing fertilizer includes mixing gelatinized starch and urea, adding the mixture of polymer water absorbing resin and formaldehyde solution, adding vegetable oil, organic matter including turf and stalk and adsorbent including zeolite, adding sulfuric acid for acidifying to obtain solid product, and final drying, crushing and sieving to obtain the product. The said process avoids excessive crosslinking of polymer to raise the utility of nitrogen, avoids volatizing of formaldehyde during reaction to raise environment quality and production efficiency, and adds zeolite and other inorganic stuffing to raise product quality and provide water maintaining and fertilizer maintaining function and trace elements. In addition, phosphate fertilizer and potash fertilizer may be also added to produce re-compounded fertilizer.

Description

technical field

[0001] The invention relates to a method for manufacturing chemical fertilizers, more specifically a method for synthesizing urea-formaldehyde controlled-release fertilizers. Background technique

[0002] Urea-formaldehyde, also known as urea-formaldehyde fertilizer, was produced by BASF in 1955 and was the first commercially produced slow-release fertilizer. Urea-formaldehyde is formed by the condensation of urea and formaldehyde, and it is white, odorless powder or granule. According to the molar ratio (U / F) of urea to formaldehyde, urea-formaldehyde fertilizers with different degrees of condensation can be prepared. Usually, the preparation process of urea-formaldehyde fertilizer: urea and formaldehyde are added into the reactor in a certain proportion to make the urea excess to prevent excessive polymerization. Usually, the molar ratio of urea to formaldehyde is controlled to be greater than 1:1, and the solution is adjusted to be alkaline with NaOH, Re...