Preparation method of humic acid coated urea

Abstract

The invention discloses a preparation method of humic acid coated urea. The preparation method comprises following steps: humic acid raw powder and trisodium phosphate are added into a sodium hydroxide or a potassium hydroxide aqueous solution for 1h of reaction at 100 DEG C so as to obtain a sodium humate or a potassium humate aqueous solution; polyvinyl alcohol is added for mixing, and an obtained mixed solution is dried until water content is lower than 10% so as to obtain a dry product; the dry product is smashed into particles with a particle size of 80 to 200 meshes, and is taken as a coating agent; at normal temperature, the coating agent is mixed with urea particles at a certain ratio; an obtained mixture is subjected to treatment in a roller for 10 to 30min, and is subjected to sieving and packaging so as to obtain humic acid coated urea. The preparation method is capable of realizing direct coating after pelleting in urea plants, and is suitable for coating processing in value-adding factories using commercial urea. Introduction of humic acid is capable of improving product functions, urea is provided with long-term stability, utilization ratio is increased greatly, the preparation method is beneficial for energy saving and environmental protection; long-term application is capable of restoring soil, increasing soil organic matter content, and improving soil self adjustment ability, and is beneficial for agricultural sustainable development.

Description

technical field [0001] The invention relates to the technical field of novel fertilizers, in particular to a preparation method of humic acid-coated urea. Background technique [0002] Humic acid (abbreviated as HA) widely exists in soil, peat, lignite, and weathered coal. It is an organic matter formed by the remains of organisms (mainly plants) through microbial decomposition and a series of geophysical and chemical processes. It is a type of complex composition. Natural organic polymer mixture. The molecular structure of humic acid is mainly composed of aromatic nucleus, and contains various functional groups such as carboxyl group, hydroxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, and methoxyl group. [0003] Humic acid is a natural plant growth regulator. A certain concentration of humic acid can promote root growth and increase germination rate; enhance plant leaf respiration and photosynthesis intensity; improve physiological metabolism and enzyme ac...

AI Technical Summary

Problems solved by technology

The existing problems of commercial urea are as follows: (1) Urea granules have poor storage stability in humid and high-temperature environments, and are easy to melt and agglomerate. Therefore, urea manufacturers generally carry out oil immersion or coating treatment, such as sulfur coating Cloth urea, etc.

But the oil may pollute the soil, and the sulfur coating process is complicated and costly

(2) The application of urea in the soil is quickly converted into ammonium nitrogen by the action of soil urease, making most of it volatilize, and the utilization rate is very low

The current technical level and existing problems of coated urea are as follows: (1) The technology of sulfur-coated urea is mature, and national standards have been formulated; however, the process is complicated, the dosage of coating agent is large, and the nitrogen content is low, which limits the application

(2) The national standard of urea inhibitor-coated urea has also passed the review (stable fertilizer), but it is highly controversial, because urease inhibitor itself is highly toxic, although it has been applied, but no long-term positioning experiment has been carried out, which is harmful to soil, environment, It is still unknown how harmful water bodies and agricultural products are

(3) Humic acid-containing urea is currently being formulated. The problem is that the amount of humic acid-containing urea is too low, only 0.12%, which is of little significance, and the slow-release and anti-caking effects of humic acid-urea in the slurry mixing method are limited. At the same time, it is easy to Make the biuret exceed the standard

However, the production and coating process of the coating agent provided by this patent are very complicated, which is not conducive to large-scale production