Method for preparing liquid fertilizer and co-producing medium element fertilizer by using raffinate acid

Abstract

The invention discloses a method for preparing a liquid fertilizer and co-producing a medium element fertilizer by using raffinate acid, and relates to the technical field of preparation of fertilizers by using raffinate acid. Comprising the following steps: S1, carrying out filter pressing on raffinate acid: adding a modified filter aid into the raffinate acid, uniformly mixing, pumping into a plate-and-frame filter press, and carrying out filter pressing to obtain a raffinate acid clear liquid and filter residues; s2, preparing a liquid fertilizer from the raffinate acid clear liquid: sequentially adding desalted water, nutrient elements, synergistic factors and the raffinate acid clear liquid into a reaction kettle, and completely dissolving to obtain an acidic liquid fertilizer; s3, preparing the medium element fertilizer from the filter residues: uniformly stirring and mixing the filter residues, phosphate tailings and a modified synergistic granulating agent, granulating, drying, screening and cooling to obtain the medium element fertilizer. The technological process is simple and easy to operate, raffinate acid is only subjected to filter pressing, the treatment cost is low, the fertilizer efficiency is improved through synergistic factors in the acid liquid fertilizer, the particle strength is improved after filter residues are granulated through the modified synergistic granulating agent, and meanwhile the medium element fertilizer is endowed with the biological stimulation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing fertilizers by using raffinate acid, and particularly relates to a method for preparing liquid fertilizer by using raffinate acid and co-producing medium element fertilizers. Background Art

[0002] With the decline of phosphate rock grade and the increasing content of impurities in dilute phosphoric acid, the proportion of raffinate acid also shows an increasing trend. Raffinate acid, as a by-product, has a complex composition, many types of impurities with high content, and a viscous phase state with poor fluidity, which is not conducive to pipeline transportation and seriously affects its normal production and application. Although the quality of raffinate acid is lower than that of ordinary phosphoric acid, the P 2 O 5 content can reach 40% or even higher, and it has gradually become the goal of comprehensive utilization of phosphorus resources. In recent years, more and more technologies for producing phosphatic fertilizers (MAP, DAP) and calcium phosphates (SSP, TSP) by using raffinate acid have become known to the public.

[0003] Patent CN116854059A discloses a method for preparing MAP and its water-soluble fertilizer by using re-raffinate acid. The method includes the following steps: adding deionized water to the re-raffinate acid, heating and decomposing it, adding sulfuric acid to obtain a pretreated acid, extracting the pretreated acid with an extraction liquid to obtain an organic phase, and back-extracting the organic phase with a back-extraction liquid to obtain crude phosphoric acid; adding Ca(OH) 2Desulfurization treatment is carried out, and the precipitate is filtered to remove the precipitate to obtain purified acid; ammonia is introduced into the purified acid to neutralize it to a pH of 4.2-4.5, and the precipitate is filtered to remove the precipitate. The filtrate is concentrated and then filtered to remove the precipitate. The filtrate is crystallized at 20-40°C, and the crystals are MAP, and the MAP is dried. Water-soluble fertilizer is prepared by mixing MAP with two of potassium sulfate, urea, and potassium nitrate. Patent CN118359456A discloses a method for purifying raffinate acid to produce high-content water-soluble fertilizer, comprising the following steps: raffinate acid is desulfurized and initially precipitated, the slag enters a superphosphate device, the clear acid enters the concentration after the initial sedimentation, the concentrated phosphoric acid enters the cooling sedimentation tank to separate impurities, and the sludge enters the superphosphate device; the separated clear acid is then subjected to an ammoniation reaction to remove impurities, and the clear liquid is then adjusted to pH value using washing acid for producing refined phosphoric acid to produce high-content water-soluble fertilizer. Patent CN118145612A discloses a method for preparing agricultural ammonium polyphosphate clear liquid using raffinate acid, comprising the following steps: filtering the raffinate acid, returning the filtered clear liquid to the purified phosphoric acid pretreatment system for purification; sending the filter residue to the ammonium phosphate production device for use; the purified clear acid enters the concentration system for concentration; pumping the concentrated acid to the tubular reactor of the ammonium polyphosphate production device to react with gaseous ammonia according to the formula mass ratio, and then the reaction slurry flows into a cooling and washing tank, and is cooled and diluted by process water to obtain an ammonium polyphosphate clear liquid product. Patent CN118343703A discloses a method for producing high-purity ammonium phosphate solution and co-producing industrial-grade MAP from raffinate acid, comprising the following steps: extracting the raffinate acid with a metal cation extractant in the first step, separating the phases to obtain an oil phase and an aqueous phase; concentrating the aqueous phase; extracting the concentrated raffinate acid with lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols, organic alkaline extractants, etc. in the second step to obtain an oil phase and an aqueous phase, and returning the aqueous phase to the raffinate acid in the first step. After repeated extraction, the raffinate acid can be used to produce a high-purity ammonium phosphate solution and industrial-grade MAP.

[0004] It can be seen that the application of raffinate in the prior art is mainly divided into two steps. The first step is that the clear liquid phosphoric acid after the raffinate is purified returns to the phosphoric acid system to normally produce ammonium phosphate or higher quality phosphoric acid or ammonium polyphosphate, etc. The second step is that the sludge is sold as a low-value commodity to superphosphate or low-nutrient compound fertilizer plants for use as raw materials; although the method for utilizing raffinate in the above patents has produced MAP, water-soluble fertilizer, high-purity ammonium phosphate solution, ammonium polyphosphate clear liquid and other phosphate-based fertilizers, and the filter residue is also sent to a low-nutrient ammonium phosphate production system or a superphosphate production device, the process operation includes multiple extractions, phase separations and filtration and impurity removal of the raffinate, the process is cumbersome and the cost is high.

[0005] Mg in raffinate 2+ 、Al 3+The high content of impurity ions such as phosphorus and phosphorus ions leads to high viscosity, which limits the efficient utilization of the residual acid. When producing fine phosphorus chemical products, it is usually necessary to pre-treat it by purification and concentration, which not only prolongs the process flow but also increases the production cost, directly limiting the reuse of the residual acid. Therefore, it is urgent to develop a low-cost and efficient utilization method. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing liquid fertilizer and co-producing medium-element fertilizer by utilizing raffinate acid, so as to solve the problems of complicated process and high cost caused by lengthy pre-purification treatment measures when utilizing raffinate acid in the prior art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for preparing liquid fertilizer and co-producing medium-element fertilizer by using raffinate acid, characterized in that the steps are as follows:

[0008] S1. Raffinate acid filtration: After adding the modified filter aid to the raffinate acid and mixing, pump it into a plate and frame filter press for filtration to obtain a raffinate acid clear liquid and a filter residue;

[0009] S2. Preparation of liquid fertilizer from raffinate solution: desalted water, nutrient elements, synergistic factors, and raffinate solution were sequentially added to the reactor and completely dissolved to obtain an acidic liquid fertilizer;

[0010] S3. Preparation of medium-element fertilizer from filter residue: The filter residue, phosphate tailings and modified synergistic granulating agent are stirred and evenly mixed, granulated, dried, sieved and cooled to obtain the medium-element fertilizer.

[0011] A further technical solution is that the preparation steps of the modified filter aid in step S1 are as follows: diatomaceous earth is slurried with water, at least one of sodium dodecyl sulfate and polyacrylamide is added, sodium hydroxide or potassium hydroxide is added, mixed, and then the mixture is dried after constant temperature treatment.

[0012] A further technical solution is that the amount of sodium dodecyl sulfate and polyacrylamide added is 10-30%, the amount of sodium hydroxide or potassium hydroxide added is 0.1-0.5%, and the constant temperature condition is 55-75°C.

[0013] A further technical solution is that the modified filter aid is added in an amount of 0.5-1.5%.

[0014] A further technical solution is that in step S2, the nutrient element is at least one of urea and potassium formate, and the synergistic factor is at least one of natamycin or potassium phosphite.

[0015] A further technical solution is that the amount of each raw material in step S2 is as follows by mass:

[0016]

[0017]

[0018] A further technical solution is that the preparation steps of the modified synergistic granulating agent in step S3 are as follows: alkalizing the refined cotton with sodium hydroxide solution to generate alkali cellulose, then adding sodium chloroacetate for kneading and etherification, then adding at least one of mineral source fulvic acid and graphene oxide, continuing etherification, and obtaining the modified synergistic granulating agent after drying and crushing.

[0019] A further technical solution is that the amount of the mineral source fulvic acid and graphene oxide added is 10-30%, the etherification temperature is 30-50° C., and the etherification time is 2-5 hours.

[0020] A further technical solution is that the amount of each raw material in step S3 is as follows by mass:

[0021] 2~35 parts of filter residue

[0022] Modified synergistic granulating agent 0.1~0.9 parts

[0023] 65-97 parts of phosphate tailings.

[0024] Reaction mechanism: Diatomaceous earth is modified by sodium dodecyl sulfate or polyacrylamide under alkaline conditions. After sodium dodecyl sulfate (SDS) is embedded in the interlayer of diatomaceous earth, the permeability of the raffinate acid is enhanced through complexation, electrostatics and ion exchange. Polyacrylamide significantly improves the destabilization and flocculation effects of solid particles through electrical neutralization, adsorption bridging and encapsulation, thereby improving the separation of acid and solid impurities, improving filtration efficiency, and enabling the raffinate acid to be efficiently separated by filter press.

[0025] The separated raffinate liquid is combined with urea (nitrogen source) and potassium formate (potassium source) to prepare liquid fertilizer with nutrient elements that meet the needs of crops, and synergistic factors are added to further enhance the ability of liquid fertilizer to promote crop growth. The residual acid in the filter residue further reacts with the phosphate tailings to obtain effective ingredients such as calcium dihydrogen phosphate and magnesium dihydrogen phosphate, and further consumes the phosphate tailings. The modified synergistic granulating agent further improves the surface properties of sodium carboxymethyl cellulose by adding mineral source fulvic acid and graphene oxide to sodium carboxymethyl cellulose, thereby improving its adhesion and mechanical properties, and ultimately making the prepared medium-element fertilizer stronger.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The process of the present invention is simple and easy to operate. The clear acid after mechanical filtration of the raffinate is directly used as the raw material for producing liquid fertilizer, without the need for complicated repeated extraction, filtration, purification and impurity removal.

[0028] 2. The present invention has low processing cost of raffinate acid. The present invention comprehensively utilizes the nutrients such as phosphorus, iron, magnesium, silicon and the like in raffinate acid to prepare liquid fertilizer products, and does not need to add extractants and flocculants, thus saving the cost of raw material processing; the iron, magnesium and silicon elements also improve the application effect of liquid fertilizer.

[0029] 3. The acidic liquid fertilizer prepared by the present invention can adjust the pH of alkaline soil, has a high market price, and improves the value of the raffinate; two synergists, potassium phosphite and natamycin, are added to the acidic liquid fertilizer, which improves the synergistic effect of the liquid fertilizer on crops.

[0030] 4. The present invention innovatively introduces modified diatomaceous earth, thereby increasing the efficiency of raffinate filtration by 12% to 30%.

[0031] 5. The present invention is based on the two-in-one synergistic granulation technology innovation, prepares a modified synergistic granulating agent, and functionalizes the granulating agent, which can not only improve the particle strength of the medium-element fertilizer, but also give the medium-element fertilizer a biostimulating effect.

[0032] 6. The present invention utilizes the raffinate acid separately after filtering, and all of it is used to produce fertilizers, without new waste liquid, solid waste, organic waste, etc., which is green, environmentally friendly, low-carbon and low-consumption, and is a new comprehensive utilization method of raffinate acid. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] S1: Raffinate acid filtration process

[0035] The main components of phosphoric acid raffinate are as follows: Total P 2 O 5 The content is 42%, the solid content is 1.5%, the iron content is 1.2%, and the magnesium content is 1.8%;

[0036] Preparation process of modified filter aid: diatomaceous earth (DE) and water are mixed in a ratio of 1:1 to form a slurry, a modifier is added to the slurry, and then 0.2% to 0.4% sodium hydroxide or potassium hydroxide is added to the slurry at a stirring rate of 300r / min, and the temperature is kept at 55 to 75°C for 45 minutes. The modifiers are added in the following ways: 15% sodium dodecyl sulfate, 15% polyacrylamide, and 25% sodium dodecyl sulfate and polyacrylamide are added in a mass ratio of 1:1. After drying, three modified filter aids are obtained for use. The modified sodium dodecyl sulfate modified diatomaceous earth is recorded as DE1, the polyacrylamide modified diatomaceous earth is recorded as DE2, and the (sodium dodecyl sulfate: polyacrylamide = 1:1) modified diatomaceous earth is recorded as DE3.

[0037] S1 Example 1

[0038] 100kg of raffinate acid was added with 0.5kg of sodium dodecyl sulfate modified diatomaceous earth (DE1), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 45 min, and 97.9 kg of clear acid and 2.6 kg of filter residue were obtained.

[0039] S1 Example 2

[0040] 100kg of raffinate acid was added with 1kg of sodium dodecyl sulfate modified diatomaceous earth (DE1), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 40 min, and 97.6 kg of clear acid and 3.4 kg of filter residue were obtained.

[0041] S1 Example 3

[0042] 100kg of raffinate acid was added with 1.5kg of sodium dodecyl sulfate modified diatomaceous earth (DE1), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 37 minutes, and 97.7 kg of clear acid and 3.8 kg of filter residue were obtained.

[0043] S1 Example 4

[0044] 100kg of raffinate acid was added with 0.5kg of polyacrylamide modified diatomaceous earth (DE2), stirred and mixed, and then pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 45 min, and 97.9 kg of clear acid and 2.6 kg of filter residue were obtained.

[0045] S1 Example 5

[0046] 100kg of raffinate acid was added with 1kg of polyacrylamide modified diatomaceous earth (DE2), stirred and mixed, and then pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 40 min, and 97.6 kg of clear acid and 3.4 kg of filter residue were obtained.

[0047] S1 Example 6

[0048] 100kg of raffinate acid was added with 1.5kg of polyacrylamide modified diatomaceous earth (DE2), stirred and mixed, and then pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 37 minutes, and 97.7 kg of clear acid and 3.8 kg of filter residue were obtained.

[0049] S1 Example 7

[0050] 100kg of raffinate acid was added with 0.5kg (sodium dodecyl sulfate: polyacrylamide = 1:1) modified diatomaceous earth (DE3), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 45 min, and 97.9 kg of clear acid and 2.6 kg of filter residue were obtained.

[0051] S1 Example 8

[0052] 100kg of raffinate acid was added with 1kg (sodium dodecyl sulfate: polyacrylamide = 1:1) modified diatomaceous earth (DE3), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 40 min, and 97.6 kg of clear acid and 3.4 kg of filter residue were obtained.

[0053] S1 Example 9

[0054] 100kg of raffinate acid was added with 1.5kg (sodium dodecyl sulfate: polyacrylamide = 1:1) modified diatomaceous earth (DE3), stirred and mixed, and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 37 minutes, and 97.7 kg of clear acid and 3.8 kg of filter residue were obtained.

[0055] S1 Comparative Example 1

[0056] 100kg of raffinate acid was mixed with 0.5kg of diatomaceous earth (DE) and pumped into a plate-frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 65 min, and 97.1 kg of clear acid and 3.4 kg of filter residue were obtained.

[0057] S1 Comparative Example 2

[0058] 100kg of raffinate acid was added with 1kg of diatomaceous earth (DE) and stirred and mixed, and then pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 58 min, and 97.2 kg of clear acid and 3.8 kg of filter residue were obtained.

[0059] S1 Comparative Example 3

[0060] 100kg of raffinate acid was mixed with 1.5kg of diatomaceous earth (DE) and pumped into a plate and frame filter press (filter chamber capacity 62.5L, filter area 5m 2 ). The filtration time was 52 minutes, and 97.4 kg of clear acid and 4.1 kg of filter residue were obtained.

[0061] Table 1 Filter Press Test Result Record

[0062]

[0063]

[0064] As shown in Table 1, in Example 1-9 in step S1, adding modified diatomite to the raffinate acid, compared with adding an equal amount of non-modified diatomite, can save 6-12 minutes of filtration time, with a minimum time saving of 12% and a maximum time saving of 30%. Comparing different addition amounts of the same modified diatomite, the larger the addition amount, the more time is saved. There is no difference in the amount of clear acid obtained in all the examples and comparative examples, and there is no difference in the amount of filter residue. Therefore, the modified diatomite of the present invention has a good filtering effect, saves time and labor, and saves time cost.

[0065] S2: Process for preparing liquid fertilizer from raffinate

[0066] The main components of the raffinate phosphoric acid solution obtained in step S1 are as follows: 2 O 5 The content is 42%, the Fe content is 1.1%, and the magnesium content is 1.6%.

[0067] Urea contains 46% nitrogen, potassium formate contains 54.5% potassium, monoammonium phosphate contains 12% N, and P 2 O 5 Content 61%.

[0068] S2 Example 1

[0069] 2m with stirring 3 Add 400kg of desalted water into the reactor, then add 115kg of urea, stir and dissolve at 100r / min at room temperature for 10-15min, then slowly add 835kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 1#, nutrient N 50g / L, P 2 O 5 350g / L.

[0070] S2 Example 2-0

[0071] 2m with stirring 3 Add 325kg of desalted water into the reactor, then add 115kg of urea and 95kg of potassium formate respectively, stir and dissolve at room temperature at 100r / min for 10-15min, then slowly add 835kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 2#-0, nutrient N 50g / L, P 2 O 5 350 g / L, K 2 O 50g / L.

[0072] S2 Example 3

[0073] 2m with stirring 3 Add 315kg of desalted water into the reactor, then add 90kg of urea, stir and dissolve at room temperature for 10-15min, then slowly add 955kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 3#, nutrient N 40g / L, P 2 O 5 400 g / L.

[0074] S2 Example 4

[0075] 2m with stirring 3 Add 195kg of desalted water into the reactor, then add 90kg of urea and 110kg of potassium formate respectively, stir and dissolve at room temperature for 10-15min, then slowly add 955kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 4#, nutrient N 40g / L, P 2 O 5 400g / L, K 2 O 60g / L.

[0076] S2 Example 5

[0077] 2m with stirring 3 Add 370kg of desalted water and 95kg of potassium formate into the reactor, stir and dissolve at 100r / min for 10-15min at room temperature, then slowly add 835kg of raffinate solution and stir and mix for 5min to obtain 1m 3 Acidic liquid fertilizer product 5#, nutrient P 2 O 5 350 g / L, K 2 O 50g / L.

[0078] S2 Example 6

[0079] 2m with stirring 3 Add 195kg of desalted water into the reactor, then add 90kg of urea and 110kg of potassium formate respectively, stir and dissolve at room temperature for 10-15min, then slowly add 955kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 6#, product nutrient P 2 O 5 400g / L, K 2 O 60g / L.

[0080] In the above embodiments, at least 1-6 kg of natamycin or potassium phosphite or a combination of the two can be added simultaneously with the addition of nitrogen or potassium source in the process of preparing liquid fertilizer according to the market demand of the product. Specific embodiments are exemplified based on Example 2-0.

[0081] S2 Example 2-1

[0082] 2m with stirring 3 Add 299kg of desalted water into the reactor, then add 115kg of urea, 95kg of potassium formate, and 6kg of potassium phosphite, stir and dissolve at room temperature at 100r / min for 10-15min, then slowly add 835kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 2#-1, nutrient N 50g / L, P 2 O 5 350 g / L, K 2 O 50g / L.

[0083] S2 Example 2-2

[0084] 2m with stirring 3 Add 299kg of desalted water into the reactor, then add 115kg of urea, 95kg of potassium formate, and 6kg of natamycin, stir and dissolve at room temperature at 100r / min for 10-15min, then slowly add 835kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 2#-2, nutrient N 50g / L, P 2 O 5 350 g / L, K 2 O 50g / L.

[0085] S2 Example 2-3

[0086] 2m with stirring 3 Add 299kg of desalted water into the reactor, then add 115kg of urea, 95kg of potassium formate, 3kg of potassium phosphite, and 3kg of natamycin, stir and dissolve at room temperature at 100r / min for 10-15min, then slowly add 835kg of raffinate solution, stir and mix for 5min, and 1m 3 Acidic liquid fertilizer product 2#-3, nutrient N 50g / L, P 2 O 5 350 g / L, K 2 O 50g / L.

[0087] S2 Comparative Example 1

[0088] 2m with stirring 3Add 299kg of desalted water into the reactor, then add 115kg of urea, 95kg of potassium formate, 580kg of monoammonium phosphate, and 5kg of xanthan gum respectively, and mix them by homogenization and emulsification for 30-45min to obtain 1m 3 Suspended liquid fertilizer product 2#-4, nutrient N 50g / L, P 2 O 5 350 g / L, K 2 O 50g / L.

[0089] The liquid fertilizer prepared in the above embodiment was stored at room temperature 25°C, low temperature 0°C, and -5°C, and the stability of the solution was observed and recorded every 3 months to provide data support for the shelf life of the product. The results are shown in Table 2.

[0090] Table 2 Test results of acidic liquid fertilizer products at room temperature and low temperature

[0091]

[0092] Note: The formula for calculating the ratio of supernatant liquid is A = height of supernatant liquid (cm) / total height of liquid (cm) * 100%

[0093] As shown in Table 2, acidic liquid fertilizers 1#, 3#, 5#, and 6# are uniform solutions with continuous stability at room temperature, low temperature of 0°C, and low temperature of -5°C for 12 months. Acidic liquid fertilizers 2# and 4# are stable liquids at room temperature for 12 months. Solids are precipitated under low temperature conditions, and the proportion of the solids is between 2% and 5%. After separation and solubility tests, the solids are fully water-soluble. Therefore, although crystallization occurs in these two formulas, once the temperature returns to room temperature, the crystals will dissolve, which will not affect product quality and sales. The solids are fully water-soluble solids and do not affect the use of spray and drip irrigation facilities for fertilization of the product.

[0094] The comparative example is a suspended liquid fertilizer made of monoammonium phosphate as the phosphorus source. Whether it is stored at room temperature or at low temperature, precipitation and stratification occur. The lower the temperature, the more serious the stratification phenomenon is. The supernatant is as high as 32% at -5°C. Compared with the comparative example, the embodiment has better product stability and longer product shelf life.

[0095] The acidic liquid fertilizer in the above embodiment was subjected to an effect verification test to provide data support for product promotion and application.

[0096] Fertilizer: Using the clear liquid fertilizer products of Examples 2#-0, 2#-1, 2#-2, and 2#-3 and the comparative product of Comparative Example 2#-4 as effect test fertilizers, a liquid fertilizer effect verification test on lettuce was carried out.

[0097] Time: March-May 2024

[0098] Trial Treatments: Treatment A: 2#-0 product 50-350-50 (without synergistic factor); Treatment B: 2#-1 product 50-350-50 + potassium phosphite (6 kg / m 3 ); Treatment C: 2#-2 product 50-350-50 + natamycin (6 kg / m 3 ); Treatment D: 2#-3 product 50-350-50 + potassium phosphite (3 kg / m 3 ) + natamycin (3 kg / m 3 ); Treatment E: The control fertilizer's phosphorus source is monoammonium phosphate 50-350-50 (pH 5.6, suspension fertilizer); Treatment CK: Water without fertilization as the control. There are 5 trial fertilizers and 1 water control, a total of 6 treatments.

[0099] Soil: Yellow soil, soil pH 7.2 (collected from the greenhouse soil in Shangsu Town, Jinning District)

[0100] Crop: Upright lettuce

[0101] Trial Design: Potted plants, with 6 treatments, 5 pots for each treatment, a total of 30 pots, randomly arranged after hanging tags.

[0102] Fertilization Frequency and Amount: Each pot is top-dressed with 2 g of liquid fertilizer each time, and at the same time 1 g of urea and 1 g of potassium chloride are applied, diluted 500 times and then watered. The first fertilization is carried out 3 days after the seedling stage, and then fertilization is carried out once every 7 days. After a total of 5 fertilizations, the yield is measured and harvested. The water control only applies water, and other normal management. The results are shown in Table 3.

[0103] Table 3 Experimental Results of the Effect of Liquid Fertilizer

[0104]

[0105] Currently, the domestic and foreign research on potassium phosphite in agriculture is mostly on sterilization, and the research on whether fertilizer application can promote crop growth is almost blank. The application of natamycin in agriculture is mostly for post-harvest fruit preservation, sterilization and disease resistance, etc. Natamycin has a strong inhibitory effect on plant pathogenic fungi, can effectively control a variety of plant fungal diseases, and natamycin can improve the stress resistance of plants, including disease resistance, drought resistance and salt tolerance, thus indirectly promoting the growth of crops. In the above experiment, the effects of single potassium phosphite, single natamycin and the compound of potassium phosphite and natamycin on the growth and development of lettuce were explored.

[0106] As shown in Table 3, from the analysis of the plant height of lettuce growth index, compared with treatment CK, the growth rates of plant height in treatments A, B, C, D, and E were 8.59%, 10.16%, 10.94%, 14.06%, and 1.56%, respectively, indicating that fertilization and fertilizers containing synergistic factors can significantly promote plant growth; compared with treatment E, the growth rates of plant height in treatments A, B, C, and D were 6.92%, 8.46%, 9.23%, and 12.3%, respectively, indicating that raffinate as a phosphorus source has a certain growth-promoting effect on plant growth compared with ammonium phosphate as a phosphorus source. The increase rates of plant height in treatments B, C, and D with the addition of synergistic factors are not much different, and the growth rates are between 8.46% and 12.3%. Among them, the effects of single adjuvant treatments of potassium phosphite and natamycin are equivalent, and the effects of adding potassium phosphite and natamycin adjuvants are more significant.

[0107] From the analysis of the average plant weight of lettuce, compared with treatment CK, the growth rates of plant weight in treatments A, B, C, D, and E were 62.9%, 67.4%, 70.0%, 87.3%, and 40.7%, respectively, indicating that the application of fertilizers and fertilizers containing synergistic factors have a good promoting effect on increasing the plant weight of lettuce, and the promoting effect of fertilizers with synergistic factors is more significant. Compared with treatment E, the growth rates of plant weight in treatments A, B, C, and D were 15.8%, 19.0%, 21.5%, and 33.1%, respectively, indicating that raffinate as a phosphorus source has a better promoting effect on plant weight than ammonium phosphate as a phosphorus source, among which the promoting effects of adding potassium phosphite and natamycin are consistent, and the promoting effect of adding both is more significant.

[0108] In summary, the experimental results show that, based on the analysis of lettuce physiological indicators and yield indicators, the liquid fertilizer prepared with raffinate acid phosphorus source has a better effect on promoting plant growth and promoting individual plants than the liquid fertilizer prepared with ammonium phosphate phosphorus source. The reason may be that raffinate acid contains magnesium and iron elements that are not found in ammonium phosphate; the liquid fertilizer prepared with raffinate acid phosphorus source with added synergistic factors is more effective; the promoting effect of the combination of potassium phosphite and natamycin is better than that of a single adjuvant.

[0109] S3: Preparation of medium element fertilizer from filter residue

[0110] The main components of the filter residue on a dry basis are: total phosphorus P 2 O 5 :24.50%; Available phosphorus P 2 O 5 :24.37%; Water-soluble phosphorus P 2 O 5 :8.02%.

[0111] Preparation process of modified synergistic granulating agent: spray 18.5% sodium hydroxide alkali solution into kneading machine, alkalize refined cotton at 30℃ to generate alkali cellulose, add solid sodium chloroacetate and knead and etherify at 30℃ for 1.5h, raise the temperature to 50℃, continue etherification for 1h (dry and crush to obtain sodium carboxymethyl cellulose CMC, which is recorded as unmodified granulating agent), add modifier, continue etherification reaction at 50℃ for 1h, dry and crush to obtain modified synergistic granulating agent. The modifiers are 15% mineral source fulvic acid, 15% graphene oxide, and 20% mixture of mineral source fulvic acid and graphene oxide in a mass ratio of 1:1. The obtained modified synergistic granulating agents are MCMC-1 (mineral source fulvic acid modification), MCMC-2 (graphene oxide modification), and MCMC-3 (mineral source fulvic acid: graphene oxide = 1:1 modification).

[0112] S3 Example 1

[0113] Take 34.5 parts of filter residue on a dry basis, 65.4 parts of phosphate tailings, and 0.1 parts of MCMC-1 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 1# medium-element fertilizer.

[0114] S3 Example 2

[0115] Take 30.6 parts of filter residue on a dry basis, 69.2 parts of phosphate tailings, and 0.2 parts of MCMC-2 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 2# medium-element fertilizer.

[0116] S3 Example 3

[0117] Take 26.6 parts of filter residue on a dry basis, 73.1 parts of phosphate tailings, and 0.3 parts of MCMC-3 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 3# medium-element fertilizer.

[0118] S3 Example 4

[0119] Take 22.7 parts of filter residue on a dry basis, 76.9 parts of phosphate tailings, and 0.4 parts of MCMC-1 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 4# medium-element fertilizer.

[0120] S3 Example 5-1

[0121] Take 18.7 parts of filter residue on a dry basis, 80.8 parts of phosphate tailings, and 0.5 parts of MCMC-1 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 5#-1 medium-element fertilizer.

[0122] S3 Example 5-2

[0123] Take 18.7 parts of filter residue on a dry basis, 80.8 parts of phosphate tailings, and 0.5 parts of MCMC-2 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 5#-2w medium-element fertilizer.

[0124] S3 Example 5-3

[0125] Take 18.7 parts of filter residue on a dry basis, 80.8 parts of phosphate tailings, and 0.5 parts of MCMC-3 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 5#-3 medium-element fertilizer.

[0126] S3 Example 6

[0127] Take 14.8 parts of filter residue on a dry basis, 84.6 parts of phosphate tailings, and 0.6 parts of MCMC-3 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 6# medium-element fertilizer.

[0128] S3 Example 7

[0129] Take 10.7 parts of filter residue on a dry basis, 88.6 parts of phosphate tailings, and 0.7 parts of MCMC-1 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 7# medium-element fertilizer.

[0130] S3 Example 8

[0131] Take 6.9 parts of filter residue on a dry basis, 92.3 parts of phosphate tailings, and 0.8 parts of MCMC-2 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 8# medium-element fertilizer.

[0132] S3 Example 9

[0133] Take 2.9 parts of filter residue on a dry basis, 96.2 parts of phosphate tailings, and 0.9 parts of MCMC-3 modified synergistic granulating agent, mix them well and perform drum granulation to obtain 100 parts of 9# medium-element fertilizer.

[0134] S3 Comparative Example 1

[0135] Take 34.5 parts of filter residue on a dry basis, 65.4 parts of phosphate tailings, and 0.1 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 1-1# medium-element fertilizer.

[0136] S3 Comparative Example 2

[0137] Take 30.6 parts of filter residue on a dry basis, 69.2 parts of phosphate tailings, and 0.2 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 2-1# medium-element fertilizer.

[0138] S3 Comparative Example 3

[0139] Take 26.6 parts of filter residue on a dry basis, 73.1 parts of phosphate tailings, and 0.3 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 3-1# medium-element fertilizer.

[0140] S3 Comparative Example 4

[0141] Take 22.7 parts of filter residue on a dry basis, 76.9 parts of phosphate tailings, and 0.4 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 4-1# medium-element fertilizer.

[0142] S3 Comparative Example 5

[0143] Take 18.7 parts of filter residue on a dry basis, 80.8 parts of phosphate tailings, and 0.5 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 5-4# medium-element fertilizer.

[0144] S3 Comparative Example 6

[0145] Take 14.8 parts of filter residue on a dry basis, 84.6 parts of phosphate tailings, and 0.6 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 6-1# medium-element fertilizer.

[0146] S3 Comparative Example 7

[0147] Take 10.7 parts of filter residue on a dry basis, 88.6 parts of phosphate tailings, and 0.7 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 7-1# medium-element fertilizer.

[0148] S3 Comparative Example 8

[0149] Take 6.9 parts of filter residue on a dry basis, 92.3 parts of phosphate tailings, and 0.8 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 8-1# medium-element fertilizer.

[0150] S3 Comparative Example 9

[0151] Take 2.9 parts of filter residue on a dry basis, 96.2 parts of phosphate tailings, and 0.9 parts of CMC granulating agent, mix them well and perform drum granulation to obtain 100 parts of 9-1# medium-element fertilizer.

[0152] The intermediate element fertilizer products in the above embodiments are summarized in Table 4.

[0153] Table 4 Product status of medium element fertilizers

[0154]

[0155]

[0156] As shown in Table 4, the total P 2 O 5 , effective P 2 O5 There were no significant differences in indicators such as total Ca, total Mg, and moisture content. Analyzing from the addition amount of the granulating agent, different addition amounts had different effects on improving the particle strength. The greater the addition amount, the stronger the effect of improving the particle strength. When the addition amount of the granulating agent was between 0.1% and 0.4%, the modified and synergistic granulating agent had a better effect on improving the particle strength than the unmodified granulating agent, and the improvement rate was between 13.82% and 16.99%. When the addition amount of the granulating agent was between 0.5% and 0.9%, the modified and synergistic granulating agent had a certain effect on improving the particle strength compared with the unmodified granulating agent, and the improvement rate was between 4.19% and 7.91%. Analyzing from the types of granulating agents, whether the modified and synergistic granulating agent was modified by a single mineral source fulvic acid, graphene oxide, or a composite modification of the two, it had a certain effect on improving the particle strength, and there were no significant differences among the modified and synergistic granulating agents.

[0157] The medium element fertilizers in the above-mentioned examples were subjected to an effect verification test to provide data support for the promotion and application of the products.

[0158] Fertilizers: The medium element fertilizers granulated with the synergistic modified granulating agents of Example 5#-1, 5#-2, and 5#-3 and the medium element fertilizer of Comparative Example 5#-4 were used as the fertilizers for the effect test, and an effect verification test of the medium element fertilizer on lettuce was carried out.

[0159] Time: March - May 2024

[0160] Test treatments: Treatment A was base-applied with 5#-1; Treatment B was base-applied with 5#-2; Treatment C was base-applied with 5#-3; Treatment D was base-applied with 5#-4; Treatment E was not base-applied; CK: Clear water without fertilization control. There were 4 test fertilizers and 1 clear water control, a total of 5 treatments.

[0161] Soil: Yellow soil, soil pH 6.1 (collected from Shangsu Town, Jinning District, greenhouse vegetable soil)

[0162] Crop: Upright lettuce

[0163] Test design: Pot experiment, with 5 treatments, 5 pots for each treatment, a total of 25 pots, randomly arranged after hanging tags.

[0164] Fertilization frequency and amount: Each pot was base-applied with 5 g of medium element fertilizer; then each pot was top-dressed with 2 g of the product 50-350-50 (without synergistic factor) of Example 2#-0 in S2, 1 g of urea, and 1 g of potassium chloride, diluted 500 times and watered. The first fertilization was carried out 3 days after the seedlings were slowed down, and then fertilization was carried out once every 7 days. After a total of 5 fertilizations, the yield was measured and harvested. The results are shown in Table 5.

[0165] Table 5 Results of the effect test of medium element fertilizers

[0166]

[0167]

[0168] As shown in Table 5, from the analysis of the plant height of lettuce growth indicators, compared with treatment CK, the growth rates of plant height in treatments A, B, C, and D were 9.78%, 6.77%, 4.51%, and 2.66%, respectively, indicating that fertilization and the application of fertilizers containing synergistic factors can effectively promote plant growth; compared with treatment D, the growth rates of plant height in treatments A, B, and C were 7.35%, 4.41%, and 2.21%, respectively, indicating that the application of medium-element fertilizers with synergistic granulation aids has a certain growth-promoting effect on plant growth, and the increase rates of plant height in treatments A, B, and C with the addition of synergistic factors are not much different, and the growth rates are between 2.21% and 7.35%, among which the addition of single modifiers of mineral source humic acid and graphene oxide and the addition of the two mutually compatible modifiers have equivalent effects.

[0169] From the analysis of the average plant weight of lettuce, compared with treatment CK, the growth rates of plant weight in treatments A, B, C, and D were 57.1%, 48.0%, 47.0%, and 43.4%, respectively, indicating that the application of fertilizers and fertilizers containing synergistic modified granulators have a good promoting effect on increasing the plant weight of lettuce, and the promoting effect of fertilizers with added adjuvants is more significant. Compared with treatment D, the growth rates of plant weight in treatments A, B, and C were 5.3%, 3.2%, and 2.5%, respectively, indicating that compared with the medium-element fertilizers granulated with unmodified granulators, the modifiers in the medium-element fertilizers granulated with the three synergistic modified granulators have a certain promoting effect on promoting the plant weight, but the promoting effect is not significant, and there is no difference between the types of modifiers.

[0170] The difference between treatment D and treatment E is that treatment D applied medium-element fertilizer as the basal fertilizer, while treatment E did not apply medium-element fertilizer as the basal fertilizer. From the data, we can see that increasing the application of medium-element fertilizer can promote the growth of plant height with a growth rate of 4.6%; increasing the application of medium-element fertilizer can promote the increase of single plant weight with an increase rate of 19.6%.

[0171] In summary, the test results show that, based on the analysis of lettuce physiological indicators and yield indicators, the application of medium-element fertilizers plays an important role in promoting plant growth and individual plant growth. The reason is that medium-element fertilizers are rich in calcium and magnesium, as well as effective phosphorus and mineral-source humic acid, graphene oxide, etc. The comparison effect between the types of synergistic granulation aids is not significant, and the reason may be that the synergist loses some synergistic activity after the synergist is modified into the granulating agent.

[0172] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing liquid fertilizer and co-producing medium-element fertilizer using raffinate, characterized in that Here are the steps: S1. Raffinate acid filtration: After adding the modified filter aid to the raffinate acid and mixing, pump it into a plate and frame filter press for filtration to obtain a raffinate acid clear liquid and a filter residue; S2. Preparation of liquid fertilizer from raffinate solution: desalted water, nutrient elements, synergistic factors, and raffinate solution were sequentially added to the reactor and completely dissolved to obtain an acidic liquid fertilizer; S3. Preparation of medium-element fertilizer from filter residue: The filter residue, phosphate tailings and modified synergistic granulating agent are stirred and evenly mixed, granulated, dried, sieved and cooled to obtain the medium-element fertilizer.

2. The method according to claim 1, characterized in that: The preparation steps of the modified filter aid in step S1 are as follows: diatomaceous earth is slurried by adding water, at least one of sodium dodecyl sulfate and polyacrylamide is added, sodium hydroxide or potassium hydroxide is added, mixed, and then the mixture is subjected to constant temperature treatment and then dried to obtain the modified filter aid.

3. The method according to claim 2, characterized in that: The amount of sodium dodecyl sulfate and polyacrylamide added is 10-30%, the amount of sodium hydroxide or potassium hydroxide added is 0.1-0.5%, and the constant temperature condition is 55-75°C.

4. The method according to claim 2, characterized in that: The modified filter aid is added in an amount of 0.5-1.5%.

5. The method according to claim 1, characterized in that: In step S2, the nutrient element is at least one of urea and potassium formate, and the synergistic factor is at least one of natamycin and potassium phosphite.

6. The method according to claim 5, characterized in that: The amount of each raw material in step S2 is as follows by mass:

7. The method according to claim 1, characterized in that: The preparation steps of the modified synergistic granulating agent in step S3 are as follows: alkalizing the refined cotton with sodium hydroxide solution to generate alkali cellulose, then adding sodium chloroacetate for kneading and etherification, then adding at least one of mineral source fulvic acid and graphene oxide, continuing etherification, and drying and crushing to obtain the modified synergistic granulating agent.

8. The method according to claim 7, characterized in that: The mineral source fulvic acid and graphene oxide are added in an amount of 10-30%, the etherification temperature is 30-50° C., and the etherification time is 2-5 hours.

9. The method according to claim 7, characterized in that: The amount of each raw material in step S3 is as follows by mass: 2~35 parts of filter residue Modified synergistic granulating agent 0.1~0.9 parts 65-97 parts of phosphate tailings.

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