Method for producing complexation metal salt of ethylenediamine tetra acetic acid

Abstract

A process for preparing a high-purity metal salt of complexon as trace-element fertilizer includes adding complexon and alkali (sodium hydroxide, potassium hydroxide, or ammonia) to water, reaction while stirring to obtain complexon salt, adding metal salt (iron hydroxide, manganese hydroxide, etc.) at 150 deg.C for 0.5-5 hr, and filter to remove insoluble substance.

Description

technical field [0001] The invention relates to a method for producing chemical fertilizers, in particular to a method for producing high-purity single EDTA complex metal salt trace element fertilizers. Background technique [0002] Existing EDTA complex metal salt production method is sulfate+EDTA 2Na+ (stabilizer urea), and its basis principle is: [0003] <chemistry num="001"> <chem file="02113215_cml001.xml" / > < / chemistry> [0004] <chemistry num="002"> <chem file="02113215_cml002.xml" / > < / chemistry> [0005] <chemistry num="003"> <chem file="02113215_cml003.xml" / > < / chemistry> [0006] <chemistry num="004"> <chem file="02113215_cml004.xml" / > < / chemistry> [0007] <chemistry num="005"> <chem file="02113215_cml005.xml" / > < / chemistry> [0008] About sulfate+EDTA 2Na+ (stabilizer urea) is introduced in documents such as Chinese patent announcement CN1102298, CN1...

AI Technical Summary

Problems solved by technology

[0013] 2. EDTA·2Na is used as a complexing agent in the process. According to the above ratio, EDTA·2Na must be greatly excessive in sulfate, which increases the cost

[0014] 3. The proportion of water added in the process is too large, so that the finished product can only be in liquid form, and the content of EDTA complex metal salt is very low, only 1-10%

[0015] 4. The solid product obtained by reaction and concentration of single sulfate + EDTA·2Na can be used in the process, but there is too much water in the reaction solution and the energy consumption is too high, which makes the cost too high and has no practical use value

Moreover, even if it is made into a solid finished product, the complex metal salt content is very low, only 25 to 40%, and has no practical use value.

[0016] 5. The quality of the finished product obtained by this process is poor. After years of actual production and application, it has been shown that there are many problems and defects:

Because of the existence of a large number of sulfate radicals, it is easy to make the soil salinized and reduce the fertilizer efficiency.

[0018] (2) Easy to leave and fall, and the applicable pH range is narrow

It can only be used in neutral soil. It is easy to precipitate EDTA in acidic environment and easy to produce metal precipitation in alkaline environment, such as Fe(OH) 2 , Zn(OH) 2 、Cu(OH) 2 , it is easy to dissociate in the soil, so that the function of trace element fertilizer is completely invalid

In fact, in our country, it is mainly alkaline soil, and the effect is often quite low when used.

[0019] (3) poor stability

In the actual production of high-efficiency compound liquid fertilizer, there is often an ion balance between sulfate and EDTA·2Na. When there are phosphate, borate, and molybdate, their insoluble metal precipitation (Zn, Mn, Cu, Fe) will appear after long-term storage. , resulting in unstable trace element fertilizers, reduced active ingredients, reduced product quality, and blocked spraying equipment

[0020] (4) Narrow application range

And because of the oxidation-reduction reaction between elements, it is impossible for all sulfates to coexist in the same solution system at the same time, thus greatly reducing the scope of application

[0021] (5) Inconvenient to use

All sulfates + EDTA·2Na+ (stabilizer urea) exist in a mixed state, and a single EDTA complex trace element fertilizer cannot be used, and it cannot enhance the effect of a single element when applied

[0022] (6) The absorption rate is not only low, but also slow to absorb, and nutrients are easily lost