Monoammonium phosphate suspension fertilizer containing medium trace elements and preparation method thereof
阅读说明：本技术 含中微量元素的磷酸一铵悬浮肥及其制备方法 (Monoammonium phosphate suspension fertilizer containing medium trace elements and preparation method thereof ) 是由 王辛龙 周小厚 许德华 许德军 张志业 杨林 钟本和 于 2020-07-06 设计创作，主要内容包括：本发明涉及含中微量元素的磷酸一铵悬浮肥及其制备方法,属于肥料技术领域。本发明解决的技术问题是提供一种含中微量元素的磷酸一铵悬浮肥的制备方法。该方法采用浓缩磷酸为原料,在螯合的同时加入悬浮剂,然后氨化、冷却成型,得到产品。本发明采用原位螯合和悬浮技术,减少了干燥工序,产品稳定均匀,能保证长期运输和储存,避免结块和分层问题,方便使用。反应所需的添加剂,用量少,成本低廉。制备的产品含固量可高达80％以上,具有良好的流变性能,营养成分高,并保留了螯合态中微量元素和全水溶性的优势,同时避免了喷雾干燥的设备和能源消耗,最终稳定性好,放置6个月以上无大颗粒聚集、无沉降,耐储存和运输。(The invention relates to a monoammonium phosphate suspension fertilizer containing medium trace elements and a preparation method thereof, belonging to the technical field of fertilizers. The invention aims to provide a preparation method of a monoammonium phosphate suspended fertilizer containing medium and trace elements. The method adopts concentrated phosphoric acid as a raw material, adds a suspending agent while chelating, and then ammoniates, cools and forms to obtain the product. The invention adopts the in-situ chelation and suspension technology, reduces the drying procedure, has stable and uniform product, can ensure long-term transportation and storage, avoids the problems of agglomeration and layering, and is convenient to use. The additive needed by the reaction is less in dosage and low in cost. The prepared product has the solid content of over 80 percent, good rheological property and high nutrient content, keeps the advantages of trace elements in a chelated state and full water solubility, avoids the consumption of spray drying equipment and energy, has good final stability, has no aggregation and sedimentation of large particles after being placed for more than 6 months, and is storage-resistant and transport-resistant.)
1. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements is characterized by comprising the following steps:
a. carrying out chelation reaction: mixing concentrated phosphoric acid with a chelating agent and a suspending agent, heating to 50-120 ℃, stirring and reacting for 30-60 min to obtain a chelated solution; wherein, the concentrated phosphoric acid contains medium trace elements;
b. ammoniation reaction: introducing ammonia gas into the chelated solution until the pH value is 4.0-5.5, and reacting at the constant temperature of 80-120 ℃ for 20-60 min to obtain high-temperature monoammonium phosphate feed liquid containing medium and trace elements;
c. and (3) cooling and forming: and cooling the high-temperature monoammonium phosphate feed liquid containing the medium trace elements to obtain the monoammonium phosphate suspended fertilizer containing the medium trace elements.
2. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: in the step a, the concentration of the concentrated phosphoric acid is 30-54 wt%, and the concentration of the concentrated phosphoric acid is P2O5Counting; preferably, the concentration of the concentrated phosphoric acid is 40-54 wt%; more preferably, the concentration of the concentrated phosphoric acid is 40 to 48 wt%.
3. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: in the step a, the chelating agent is ethylenediamine tetraacetic acid or citric acid; the suspending agent is at least one of carboxymethyl cellulose, xanthan gum, polyglutamic acid, diamino dimethyl monopropanol, hydroxyethyl cellulose, polyacrylamide and sodium alginate.
4. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: in the step a, the dosage of the chelating agent is 1.0-2.0 times of the theoretical dosage required for carrying out a chelating reaction with the medium trace elements in the wet-process phosphoric acid, the dosage of the suspending agent is 0.0001-0.01 times of the weight of the concentrated phosphoric acid, and the dosage of the suspending agent is preferably 0.0003 times of the weight of the concentrated phosphoric acid.
5. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: in step a, the reaction is carried out at 80 ℃ for 30 min.
6. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: and b, reacting at constant temperature of 100 ℃ for 40 min.
7. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to claim 1, which is characterized by comprising the following steps: and c, uniformly stirring and cooling at a constant speed.
8. The preparation method of the monoammonium phosphate suspended fertilizer containing medium and trace elements according to any one of claims 1 to 7, which is characterized by comprising the following steps: the medium trace element is at least one of Fe, Mg, Ca, Mn, Cu and Zn.
9. The medium trace element-containing monoammonium phosphate suspended fertilizer prepared by the method for preparing the medium trace element-containing monoammonium phosphate suspended fertilizer according to any one of claims 1 to 8.
Technical Field
The invention relates to a monoammonium phosphate suspension fertilizer containing medium trace elements and a preparation method thereof, belonging to the technical field of fertilizers.
Background
With the rapid development of the water-fertilizer integration technology, the advantages of liquid fertilizer products are increased year by year, and the development trend of full-speed dissolving, compounding, liquefying and concentrating fertilizers is more and more obvious. The liquid fertilizer has the advantages of uniform component composition, high nutrient activity, flexible formula, convenient use, wide raw material source, simple production and the like, and is popular with the majority of users. The prior liquid fertilizer comprises a clear liquid type and a suspension type. Industrial grade monoammonium phosphate (MAP) is a basic raw material of a high-quality macroelement water-soluble fertilizer, has been widely applied to agriculture at home and abroad, is an important basic fertilizer for realizing water and fertilizer integration in China, and has great potential for developing high-content liquid water-soluble fertilizers. In recent years, with the transformation requirement of the chemical fertilizer industry in China, the demand of the country for industrial grade monoammonium phosphate is continuously increased, and the development and the upgrading of full water-soluble fertilizer products with high nutrient content are continuously promoted.
In order to meet the requirement of water and fertilizer integration, the water-soluble liquid fertilizer can be completely dissolved and is easy to apply, so that the water-soluble liquid fertilizer is widely accepted. However, most of the prior clear liquid fertilizers have low nutrient content and high cost, which hinders the application and development. At present, the traditional compound fertilizer in China has excess capacity, most of fertilizer raw materials come from chemical engineering and minerals, and the fertilizer contains more medium and trace elements and is easy to form insoluble substances, so that technical upgrading and research on high-nutrient water-soluble suspended fertilizer products are urgently needed to adapt to the development of water-fertilizer integration. The suspended fertilizer system is a slurry type fertilizer in a supersaturated state, contains higher nutrients and has low production and transportation cost. However, the suspended fertilizer has the problems of unstable system and easy sedimentation, and the problem is particularly serious especially when the solid content is high.
Chinese patent publication No. CN106748296A discloses a high-concentration suspension type liquid fertilizer and a preparation method thereof, wherein insoluble substances in the fertilizer are suspended in a system by using a suspension auxiliary agent, a specific nano-pore colloidal particle is added as a crystal growth inhibitor, the nano-pores of the colloidal particle have a large enough surface area and a chelating agent in the nano-pores can adsorb and collect crystal particles, the aggregation and the growth of crystal particles newly precipitated in the storage process of the liquid fertilizer are limited by the spatial effect of the dispersion of the colloidal particle, and the dispersibility of the suspension fertilizer can be effectively improved, so that the high-concentration suspension fertilizer is stably suspended for a long time. The investment of the nano-pore colloidal particles obviously improves the cost of the product, and simultaneously, the insoluble substances are still only suspended, so that the hidden trouble problem of unstable full water solubility exists.
Chinese patent 201410208635.0 discloses a suspending agent and a method for solving the problem of high concentration liquid fertilizer stratification by using the same, wherein the suspending agent is a compound auxiliary agent consisting of xanthan gum, polyglutamic acid and activated clay, and the viscosity of the suspending agent is improved in a high concentration suspending system. Thereby improving the quality of the developed suspension fertilizer and pursuing the characteristics of high concentration, low water content and good fluidity. Although the clay mineral is adopted for the selection of the thickening agent, the cost is reduced, the problem of low viscosity of the clay mineral still exists, the thickening effect in the liquid fertilizer is not obvious, and the liquid fertilizer product is easy to settle in a short time.
Chinese patent publication No. CN105085049A discloses a high-nitrogen suspended liquid fertilizer and a preparation method thereof, wherein the thickening properties of Arabic gum, sodium carboxymethylcellulose, xanthan gum, white carbon black and bentonite are utilized to increase the stability of a suspended fertilizer system. However, the addition of auxiliaries requires a relatively large amount to produce a stable suspension, which causes significant cost problems.
Chinese patent publication No. CN108440146A discloses a high-concentration full-nutrition functional suspension liquid fertilizer and a preparation method thereof. The functional additive and the preparation formula are provided, and the functional additive is prepared by adding and mixing 1-5 parts of functional additive, 40-60 parts of macroelement fertilizer, 1-5 parts of medium element fertilizer, 0.5-2.5 parts of trace element fertilizer, 0.5-2.5 parts of suspending agent and 20-40 parts of water in a specific order, and then homogenizing and emulsifying. The product is rich in nitrogen, phosphorus, potassium and medium trace elements, the functional auxiliary agent contained in the product positively promotes the growth of plants, has a conditioning effect on soil, can ensure full water solubility and fluidity, and is suitable for a water-soluble fertilizer integrated irrigation system. The main process of the high-concentration water-soluble fertilizer is still prepared by means of the conventional nutrient product through a fertilizer preparation mode, trace elements are required to be added at the outer edge, the cost is increased by adding a high proportion of functional additives, and the hidden danger of caking and layering caused by long-term storage is possibly caused in a mixing and preparing mode, so that the problems of caking, indissolvability, pipe blockage and the like during use are caused.
Chinese patent publication No. CN109627109A discloses a water-retaining liquid suspended fertilizer and a preparation method thereof, wherein the water-retaining liquid suspended fertilizer comprises the following raw materials in parts by weight: 27-29 parts of humic acid, 6-8 parts of nitrogenous fertilizer, 5-11 parts of phosphatic fertilizer, 7-8 parts of potash fertilizer, 1-2 parts of boric fertilizer, 0.5-1 part of EDTA-Fe, 0.5-1 part of EDTA-Zn, 0.5-1 part of EDTA-Mn, 7-10 parts of water-retaining agent, 3-5 parts of tea stalk, 1-2 parts of wetting dispersant, 1.6-3 parts of emulsifier, 1-4 parts of thickener, 0.5-1 part of preservative and 0.5-1 part of anticaking agent. The product provided by the invention contains major elements such as humic acid, nitrogen, phosphorus, potassium and the like and trace elements such as boron, zinc and the like, and achieves the effects of water saving and water retention by utilizing the water absorption effect of the water retention agent. However, trace elements in the product still need to be added into finished chelated products (EDTA-Fe, EDTA-Zn and EDTA-Mn), so that the cost is higher, the types of the added auxiliaries are more, and the integral proportion is also higher.
Chinese patent publication No. CN104591930B discloses a slow-release suspension liquid compound fertilizer, which adopts a mixed formulation: 30-200 parts of fertilizer nutrient substances, 0.05-2 parts of thickening agent, 0.1-4 parts of suspending agent, 0.1-3 parts of emulsifying agent, 0.05-1 part of nitrification inhibitor and 0-15 parts of water, wherein the fertilizer nutrient substances comprise nitrogen fertilizer, phosphate fertilizer, potash fertilizer, humic acid and trace elements, and contain at least one quick-acting fertilizer and at least one slow-acting fertilizer. The invention has all the advantages of the existing suspension formulation, provides the ternary liquid fertilizer containing quick-acting and slow-acting nutrients, trace elements and humic acid, and prolongs the fertilizer efficiency of the suspension fertilizer. However, the product has complex preparation flow, more types of required nutrients and auxiliary agents, higher cost and larger difficulty in large-scale production.
Chinese patent publication No. CN106242831A discloses a preparation method of a suspended fertilizer, wherein a dispersing agent and a defoaming agent are uniformly mixed in an emulsifying machine according to a certain mass ratio, then a large amount of elements, a medium amount of elements, trace elements and auxiliary materials are added according to a certain mass ratio, the materials in the emulsifying machine are sheared for 10-30 min under the control of temperature, finally a thickening agent and the defoaming agent are added, and the suspended fertilizer is obtained after uniform stirring. The suspension fertilizer has stable quality and is not layered. However, the product is prepared from the existing nutrient raw materials, is assisted by the additive, and needs to be processed by high-speed shearing equipment, so that the production input cost is increased.
In conclusion, most of the existing high-solid content liquid water-soluble fertilizer products are physically compounded by using nutrient raw material finished products and are matched with various additives to prepare suspended fertilizer products, the suspension effect is realized by means of nutrient compatibility technology and suspending agents, and the problem of aggregation and settlement of fine particles in a short period is solved by means of dispersion, grinding, thickening and the like. However, the suspended fertilizer product belongs to supersaturated liquid, is prepared by blending while being in an unstable state, and is easy to grow and agglomerate due to the influence of external force, temperature, pH value and the like after being stored for a long time, so that the suspended fertilizer is finally subjected to solid-liquid separation. And the raw materials are high in compounding price, and the trace elements are also added from the outer edge chelate, so that the cost is greatly increased. The unstable system of physical compounding is still easy to agglomerate after being stored for a long time, so that large particles sink to the water bottom in the process of water and fertilizer integrated fertilization, and are difficult to uniformly disperse through stirring, even block pipelines. This drawback is particularly evident in high concentration suspended fertilizers.
Disclosure of Invention
Aiming at the defects, the invention provides a preparation method of a monoammonium phosphate suspended fertilizer containing medium and trace elements.
The invention relates to a preparation method of a monoammonium phosphate suspension fertilizer containing medium trace elements, which comprises the following steps:
a. carrying out chelation reaction: mixing concentrated phosphoric acid with a chelating agent and a suspending agent, heating to 50-120 ℃, stirring and reacting for 30-60 min to obtain a chelated solution; wherein, the concentrated phosphoric acid contains medium trace elements;
b. ammoniation reaction: introducing ammonia gas into the chelated solution until the pH value is 4.0-5.5, and reacting at the constant temperature of 80-120 ℃ for 20-60 min to obtain high-temperature monoammonium phosphate feed liquid containing medium and trace elements;
c. and (3) cooling and forming: and cooling the high-temperature monoammonium phosphate feed liquid containing the medium trace elements to obtain the monoammonium phosphate suspended fertilizer containing the medium trace elements.
In an embodiment of the present invention, the concentrated phosphoric acid has a concentration of 30 to 54 wt%. The phosphoric acid concentration of the invention is P2O5And (6) counting. In some embodiments of the present invention, the concentration of concentrated phosphoric acid is 40 to 54 w%. In a specific embodiment, the concentration of the concentrated phosphoric acid is 40 to 48 wt%.
In order to increase the chelating effect, the chelating agent is preferably citric acid or EDTA.
In some embodiments, the suspending agent is at least one of carboxymethyl cellulose, xanthan gum, polyglutamic acid, diaminodimethyl-propanol, hydroxyethyl cellulose, polyacrylamide, and sodium alginate.
Preferably, the dosage of the chelating agent is 1.0-2.0 times of the theoretical dosage required for the chelating reaction with the medium trace elements in the mixed solution.
In some embodiments of the invention, the suspending agent is added in an amount of 0.0001 to 0.01 times the weight of the concentrated phosphoric acid. In one embodiment, the suspending agent is present in an amount of 0.0003 times the weight of the concentrated phosphoric acid.
In a specific embodiment, in step a, chelation reaction is carried out at 80 ℃ for 30 min.
In one embodiment of the invention, in the step b, the reaction is carried out at 100 ℃ for 40 min.
In a specific embodiment, in the step c, the cooling is uniform stirring and uniform cooling.
The medium trace elements in the monoammonium phosphate suspended fertilizer containing the medium trace elements are all derived from wet-process phosphoric acid, and in some embodiments of the invention, the medium trace elements are at least one of Fe, Mg, Ca, Mn, Cu and Zn.
The invention also provides the monoammonium phosphate suspended fertilizer containing medium and trace elements, which is prepared by the method.
The monoammonium phosphate suspension fertilizer containing medium and trace elements is prepared by the method. The product has solid content of above 80%, high nutrition, retained trace elements in chelate state and full water solubility, good stability, no aggregation and settlement of large particles after standing for more than 6 months, and good storage and transportation resistance.
Compared with the prior art, the invention has the following beneficial effects:
1. the method takes the concentrated wet-process phosphoric acid as a raw material, produces the phosphoric acid in situ, has simple preparation process, can adjust process conditions to produce monoammonium phosphate with different medium and trace element contents, fully utilizes impurity ions in the wet-process phosphoric acid, converts the impurity ions into chelated medium and trace elements, can stimulate the physiological metabolism of plants, enhances the stress resistance, and improves the yield and the quality of crops. Simultaneously, the production of white fertilizer is avoided, and P is improved2O5The utilization rate of the method is reduced, and the production cost is reduced. The product is fully water-soluble, non-toxic and harmless, is easy to degrade in natural environment, is environment-friendly, and can be widely applied to facility agriculture such as water and fertilizer integration.
2. The product prepared by the method has the advantages of solid content of over 80 percent, high nutrient content, reservation of the advantages of trace elements in a chelated state and full water solubility, avoidance of spray drying equipment and energy consumption, good final stability, no aggregation of large particles and no sedimentation after being placed for more than 6 months, and storage and transportation resistance.
3. The invention adopts the in-situ chelation and suspension technology, reduces the drying process, has good product stability and uniformity, can ensure long-term transportation and storage, avoids the problems of agglomeration and layering, and is convenient to use. The additive needed by the reaction is less in dosage and low in cost. The product belongs to non-Newtonian fluid, has good rheological property, can rapidly improve the fluidity by slightly stirring or kneading and the like when in use, and is convenient to use.
Detailed Description
The invention relates to a preparation method of a monoammonium phosphate suspension fertilizer containing medium trace elements, which comprises the following steps:
a. carrying out chelation reaction: mixing concentrated phosphoric acid with a chelating agent and a suspending agent, heating to 50-120 ℃, stirring and reacting for 30-60 min to obtain a chelated solution; wherein, the concentrated phosphoric acid contains medium trace elements;
b. ammoniation reaction: introducing ammonia gas into the chelated solution until the pH value is 4.0-5.5, and reacting at the constant temperature of 80-120 ℃ for 20-60 min to obtain high-temperature monoammonium phosphate feed liquid containing medium and trace elements;
c. and (3) cooling and forming: and cooling the high-temperature monoammonium phosphate feed liquid containing the medium trace elements to obtain the monoammonium phosphate suspended fertilizer containing the medium trace elements.
The invention provides a novel process for directly producing a suspended water-soluble fertilizer containing medium and trace elements and high solid content by utilizing wet-process phosphoric acid by combining an element chelation and system suspension technology from a low-cost water-soluble phosphorus source, wherein concentrated wet-process phosphoric acid containing medium and trace elements is directly used as a raw material, and the medium and trace metal elements in the concentrated phosphoric acid are chelated, so that the prepared product contains monoammonium phosphate and medium and trace elements, is a full water-soluble fertilizer, provides N, P nutrient elements for plants, also provides medium and trace elements necessary in the growth process for the plants, is prepared by reaction in a high-concentration system, greatly improves the nutrient content, ensures the uniformity and stability of the system, and can be stored and transported for a long time. The nutrient particles and the addition auxiliary agent are well cooperated, the product belongs to non-Newtonian fluid, has good rheological property, can rapidly improve the fluidity by slightly stirring or kneading and the like when in use, and is convenient to use.
Step a is a chelating step, and a chelating agent and a suspending agent are added, so that medium and trace elements in wet-process phosphoric acid are chelated, and the space stability and the static stability among particles in a system generated by reaction can be adjusted in situ.
In order to ensure high solid content, in the embodiment of the invention, the concentration of the concentrated phosphoric acid is 30-54 wt%. The phosphoric acid concentration of the invention is P2O5And (6) counting. The concentration of the common wet-process phosphoric acid is generally 18-26 wt%, namely the phosphoric acid is concentrated by 1.5-2.0 times. In some embodiments of the invention, the concentrated phosphoric acid concentration is from 40 wt% to 54 wt%. In a specific embodiment, the concentration of concentrated phosphoric acid is 40 wt% to 48 wt%.
Chelating agents commonly used in the art are suitable for use in the present invention, and in the examples of the present invention, the chelating agent may be ethylenediaminetetraacetic acid (EDTA), disodium ethylenediaminetetraacetic acid (EDTA-2Na), tetrasodium ethylenediaminetetraacetate (EDTA-4Na), diammonium ethylenediaminetetraacetate, triammonium ethylenediaminetetraacetate, dimethylenetriaminepentaacetic acid, potassium ethylenediaminetetraacetate, disodium ethylenediaminetetraacetate dihydrate, diethylenetriaminepentaacetic acid (DTPA), pentasodium diethylenetriaminepentaacetate (DTPA-5Na), Triethylenediamine (TEDA), propylenediaminetetraacetic acid (PDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), trisodium hydroxyethylethylenediaminetriacetic acid (HEDTA-3Na), hydroxyethylethylenediamine (AEEA), trisodium hydroxyethylethylenediaminetetraacetate, sodium dihydroxyethylglycinate, sodium nitrilotriacetate, nitrilotriacetic acid, nitrilotriacetic acid trisodium salt, nitrilotriacetic acid trisodium salt monohydrate, hydroxyethyl diphosphonic acid, ethylenediamine diphthalacetic acid (EDDHA), ethylenediamine diphthalic acid sodium salt (EDDHA-Na), hydroxyethylidene diphosphonic acid and its potassium, sodium, ammonium salts, aminotrimethylene phosphonic acid and its potassium, sodium, ammonium salts, ethylenediamine tetramethylene phosphonic acid and its potassium, sodium, ammonium salts, diethylenetriamine pentamethylene phosphonic acid and its potassium, sodium, ammonium salts, 2-phosphonic acid butane-1, 2, 4-tricarboxylic acid and its potassium, sodium, ammonium salts, polyol phosphates, 2-hydroxyphosphonic acid and its potassium, sodium, ammonium salts, hexamethylenediamine tetramethylene phosphonic acid and its potassium, sodium, ammonium salts, polyamino polyether methylene phosphonic acid and its potassium, sodium, ammonium salts, bis 1, 6-hexamethylenetriamine pentamethylene phosphonic acid and its potassium, sodium, ammonium salts, triethylenetetramine hexaacetic acid and its potassium, sodium, ammonium salts, triethylenetetramine hexaacetic acid and its potassium, Sodium, ammonium salts, dihydroxyethylglycine and its potassium, sodium, ammonium salts, 2-oxoacetoxymalonic acid and its potassium, sodium, ammonium salts, 2-oxoacetoxybutyroic acid and its potassium, sodium, ammonium salts, 1,2,3, 4-cyclopentanetetracarboxylic acid and its potassium, sodium, ammonium salts, acetic acid and its potassium, sodium, ammonium salts, citric acid, potassium citrate, monosodium citrate, phytic acid, gluconic acid, sodium gluconate, potassium gluconate, glucose-lactone, sodium pyrophosphate, sodium tripolyphosphate, potassium pyrophosphate, (poly) sodium polyphosphate, (poly) ammonium polyphosphate, hexametaphosphoric acid, sodium hexametaphosphate, potassium hexametaphosphate, ammonium hexametaphosphate, glucoheptonic acid and its potassium, sodium, ammonium salts, sorbitol syrup, carboxymethyloxysuccinic acid, carboxymethyltartaric acid, tartaric acid and its sodium salts, tartaric acid and its potassium salts, naphthalenetrisulfonic acid, maleic acid, amino acids and their potassium, sodium, ammonium salts, lignosulfonic acid and its soluble salts, valeric acid, pentenoic acid, pentasodium pentenoate, humic acid and its potassium, sodium, ammonium salts, oxalic acid and its potassium, sodium, ammonium salts, alginic acid and its potassium, sodium, ammonium salts, sugar alcohols, mannitol, xylitol, malic acid and its potassium, sodium, ammonium salts, fulvic acid and its potassium, sodium, ammonium salts, lignosulfonic acid and its potassium, sodium, ammonium salts, HBED, EDDMA, polyacrylic acid and its potassium, sodium, ammonium salts, polyethylene glycol, formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malonic acid, fumaric acid, citric acid, ascorbic acid, succinic acid, glycolic acid, polymethacrylic acid, hydrolyzed polymaleic anhydride, maleic acid-acrylic acid copolymers, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid multipolymers, acrylic acid hydroxypropyl acrylate copolymers, acrylic acid-acrylate-phosphonic acid-sulfonate tetrapolymer, acrylic acid-acrylate-sulfonate terpolymer, carboxylate-sulfonate-nonionic terpolymer, polyepoxysuccinic acid (sodium), polyaspartic acid (sodium), ethylenediamine, 2,2' -bipyridine, 1, 10-phenanthroline, sodium aminotriacetate, iminodiacetic acid, tetrasodium iminodisuccinate, trisodium ethylenediamine disuccinate (IDS), waste acid or filter mud in sugar manufacturing industry, furfural and waste residue thereof, high-concentration organic waste liquid discharged in alcohol and monosodium glutamate production, fermentation waste liquid, livestock excrement and biogas slurry thereof, amino acid waste liquid and the like.
In order to increase the chelating effect, the chelating agent is preferably citric acid or EDTA.
The addition amount of the chelating agent is related to the content of the medium trace elements in the raw materials, the content of the medium trace elements in the concentrated wet-process phosphoric acid is high, or the amount of the chelating agent required to be added is high when the amount of the medium trace elements added in the phosphoric acid is high, the content of the chelated medium trace elements in the final product is correspondingly high, and vice versa. Preferably, the dosage of the chelating agent is 1.0-2.0 times of the theoretical dosage required for the chelating reaction with the medium trace elements in the mixed solution.
The addition of the suspending agent can adjust the space stability and the electrostatic stability among particles in a system generated by the reaction in situ. In some embodiments of the invention, the suspending agent is at least one of carboxymethyl cellulose, xanthan gum, polyglutamic acid, diaminodimethyl-propanol, hydroxyethyl cellulose, polyacrylamide and sodium alginate.
In the step a, the suspension aid is added in the chelation step to ensure that the suspending agent can be uniformly dispersed in a reaction system, so that small ammonium phosphate particles formed after ammoniation are ensured to be in timely and uniform contact with the suspension aid, the steric hindrance and the electrostatic stability can be quickly established among the particles, and a better suspension effect is ensured.
The suspending agent is required to be uniformly dispersed in a reaction system, so that small ammonium phosphate particles formed after ammoniation are ensured to be in timely and uniform contact with the suspension auxiliary agent, the steric hindrance and the electrostatic stability can be quickly established among the particles, and a better suspension effect is ensured. The suspending agent can resist high temperature and stably coexist with high-concentration salt solution, has a special macromolecular structure and colloid characteristic, and can maintain the suspending function in a chelating step and an ammoniation reaction. However, due to the limitation of material properties, the suspending agent has a complex dissolution process and is easily agglomerated to form colloidal agglomerates, and uniform mixing is required to ensure the effectiveness and uniform dispersion effect. If the suspension agent is added in the subsequent ammoniation reaction process, the local temperature is easily too high, so that the suspending agent solution is rapidly agglomerated to form sticky floccules, the sticky floccules cannot be uniformly dispersed, the suspension function is lost, and the solubility of the final product is greatly reduced. Thus, the suspending agent of the present invention is added in the chelation step.
In some embodiments of the invention, the suspending agent is added in an amount of 0.0001 to 0.01 times the weight of the concentrated phosphoric acid. In one embodiment, the suspending agent is present in an amount of 0.0003 times the weight of the concentrated phosphoric acid.
As a specific embodiment, the chelating agent and suspending agent addition temperature are maintained consistent, and consistent with the temperature of the chelation reaction.
In a specific embodiment, in step a, chelation reaction is carried out at 80 ℃ for 30 min.
And b, performing an ammoniation reaction process, wherein the reaction temperature is 80-120 ℃, and the reaction temperature can be adjusted according to the concentration of the wet-process phosphoric acid. In one embodiment of the invention, the reaction temperature is 100 ℃.
The pH value of the final point of the ammoniation reaction is 4.0-5.5, and the pH value can be adjusted according to different chelating agents and reaction temperatures. In one embodiment of the invention, ammonia gas is introduced, and the reaction is carried out at 100 ℃ and then the reaction is kept for 40min for stabilization. The obtained liquid is high-temperature monoammonium phosphate feed liquid containing medium and trace elements. The feed liquid contains impurity ions in the wet-process phosphoric acid, such as Fe, Mg, Ca, Mn, Cu, Zn, and the like.
And c, preparing the high-solid-content full-water-soluble monoammonium phosphate suspended fertilizer containing the medium trace elements from the high-temperature monoammonium phosphate feed liquid containing the chelated medium trace elements.
In one embodiment of the invention, the fully water-soluble monoammonium phosphate suspension fertilizer containing medium and trace elements is obtained by adopting a direct cooling mode. In a specific embodiment, the fully water-soluble monoammonium phosphate suspension fertilizer containing medium and trace elements is prepared by uniformly stirring and cooling at a constant speed.
The medium trace elements in the monoammonium phosphate suspended fertilizer containing the medium trace elements are all derived from wet-process phosphoric acid, and in some embodiments of the invention, the medium trace elements are at least one of Fe, Mg, Ca, Mn, Cu and Zn.
The invention also provides the monoammonium phosphate suspended fertilizer containing medium and trace elements, which is prepared by the method.
The monoammonium phosphate suspension fertilizer containing medium and trace elements is prepared by the method. The product has solid content of above 80%, high nutrition, retained trace elements in chelate state and full water solubility, good stability, no aggregation and settlement of large particles after standing for more than 6 months, and good storage and transportation resistance.
In the present invention, "%" is a weight percentage unless otherwise specified.
The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.