GB2034682A

GB2034682A - High Analysis Liquid Fertilizer

Info

Publication number: GB2034682A
Application number: GB7900196A
Authority: GB
Original assignee: Stoller Enterprises Inc
Current assignee: Stoller Enterprises Inc
Priority date: 1978-10-30
Filing date: 1979-01-03
Publication date: 1980-06-11
Also published as: IT7948941A0; FR2440346B1; DE2902651A1; BR7901753A; CA1118225A; AU523286B2; IT1116813B; FR2440346A1; ZA79607B; GB2013167B; GB2034682B; GB2013167A; AU4362779A

Abstract

High analysis liquid fertilizers comprising the reaction product of urea and phosphoric acid having a pH between 1.5 and 4 and optionally containing the reaction product of urea and sulfuric acid, various trace elements normally found as contaminates in the lower grades of wet process phosphoric acid, potash and gelling agents, said fertilizers being further characterized as having total analysis of N, P2O5 and K2O of at least 25 weight percent and preferably 30 weight percent or greater. <IMAGE>

Description

1

SPECIFICATION High Analysis Liquid Fertilizers

GB 2 034 682 A 1 The present invention relates to high analysis liquid fertilizer compositions and the method of preparing said compositions.

Modern agriculture is based on appropriate fertilization. The cost of acquiring and applying nutrients is dominant, and much effort on the part of many investigators has been directed at improving the cost-effectiveness of fertilizer systems and practices. As a result of these efforts, liquid fertilizers are growing in acceptance because of economics in application and placement; products of higher analysis have become available, leading to cost reduction all along the line from the point of manufacture to application in the field.

Prior Art

Much work has been done in the past on the production of high analysis liquid fertilizers. For example, U.S. Pat. No.'s 2,770,538 and 2,869,996 describe liquid products made from phosphoric acid neutralized with ammonia and potassium hydroxide, to which is added urea or ammonia plus nitric acid tofurnish additional nitrogen. U.S. Pat. No. 2,814,556 shows how to combine urea, ammonia, 15 phosphoric acid and potassium chloride to make neutral liquids of high analysis containing ammonium phosphate. U.S. Pat. No. 3,022,153 teaches the combination of urea, wet-process phosphoric acid and ammonia; stabilization with amines is required in storageperiods greater than a few days are contemplated. Complexes of urea and micronutrient metals are described in U.S. Pat. No. 3,640,698; to these may be added moderate amounts of other nutrients to form liquid systems of low pH and low 20 analysis. In U.S. Pat. No. 3,713,802 a process is described for reacting urea and wet process phosphoric acid, separating the precipitated urea-phosphate and ammoniating it to convert it into commercially useful grades of liquid or solid fertilizer; in this process, separation of the urea-phosphate by precipitation and filtration is required to remove contaminants present in the phosphoric acid.

Similarly, U.S. Pat. No. 3,723,086 discloses reacting merchant grade wet process phosphoric acid and 25 urea followed by ammoniation to.product liquid fertilizers. U.S. Pat. No. 3,918,952 uses potassium chloride, urea and ammonium polyphosphate to make high analysis liquids; in these products, potassium chloride is the only form of potash compatible with the other ingredients, and relatively expensive polyphosphates must be used.

Generally in the prior art, high analysis liquids are achieved by using expensive furnace grade 30 acid, or by removing contaminants from wet process acid by costly processing, or by converting orthophosphoric acid to polyphosphoric acid by heat treatment. The products are usually neutralized to pH values ranging from 6 to 8.7 for stability and achievement of the required analysis, with some exceptions as noted above (U.S. Pat. No. 3,640,698).

Liquid fertilizers provide opportunities for further savings in several key areas including:

1. Production of higher analysis compounds 2. Use of lowest cost components 3. Provision of formulating flexibility so that the desired precise nutrient ratios can be made from a minimum number of simple components 4. Simplification of the compounding process and equipment so that it can be moved as close as 40 possible to the point of application 5. Incorporation of trace and secondary elements from low-cost inorganic sources 6. Maximizing agronomic efficiency, especially with regard to nitrogen retention and utilization in the soil and phosphate availability.

All of these elements have been addressed in the current invention, and what results is a novel 45 method of producing novel liquid fertilizers.

It is an advantage of the present invention that liquid fertilizers having high total nutrient content according to commercial standards may be prepared. It is a further advantage of the invention that these liquid fertilizers are prepared autothermally, without recourse to external heating. Its a feature of the present invention that the liquid fertilizers may be prepared from a limited number of components. 50 It is a particular feature that the liquid fertilizers may be manufactured in simple equipment, that is readily available and low in cost, using straight forward processing procedures that can be easily mastered by compounders. It is a further feature of the present invention that the liquid fertilizers may be made quickly. it is a particular advantage of the present process that commercial grades of components may be satisfactorily employed to produce the fertilizers.

It is a further advantage that the liquid fertilizers of this invention exhibits commercially acceptable stability over the full range of nutrient content. In addition, it is a particular advantage that the present invention allows inclusion of secondary and trace elements in stable and available form without prior art chelated or complexed products.

A further advantage of the present invention is the provision of complete liquid fertilizer compositions in which nitrogen and phosphate availability are maximized. In so doing, one of the features of the present invention is the preparation of a complete range of liquid fertilizers containing combinations of the primary nutrients, nitrogen, phosphorus and potassium, wherein N may range up i 2 GB 2 034 682 A 2 to 30 weight percent, P20, up to 54 weight percent and K20 up to 30 weight percent.

A further particular feature of the present invention is to provide fertilizers of improved agronomic efficiency.

Basically the present invention concerns high analysis liquid fertilizers comprising the reaction product of urea and phosphoric acid, having a pH less than 4, preferably less than 2 and generally from about 1.5 to 2.0. The solutions are clear and stable against salting out at OC. Generally up to 2 moles of urea per mole of phosphoric acid may be employed without dilution water. When sulfuric acid is present in addition to phosphoric, up to about 3 moles of urea may be added (depending on the amount of sulfuric acid present, since 3 moles of urea will react with sulfuric acid alone to form OOC stable solutions). The minimum amount of urea is that desired but usually at least one mole per mole of 10 acid would be used.

In the process of preparing these compositions, it has been found that where the ratio of nitrogen weight content to P201 weight content is 0.61, or greater, the phosphoric acid should advantageously be added directly to the urea. Preferably the urea has been dampened or slurried with water prior to acid addition. However, where the weight ratio of nitrogen to P20, is less than 0.61, the urea maybe 15 added directly to the phosphoric acid.

The procedure of adding the phosphoric acid to the urea when the weight ratio of N:P20, is 0.61 or greater avoids crystallization or salting out that would normally result. (Note U.S. Pat. No.

3,713,802, cols. 4 and 5).

This invention is particularly well adapted to the utilization of commercial grades of phosphoric 20 acid and/or urea. The acids are frequently contaminated with trace metals for example, zinc, manganese and iron, which can be useful components of the fertilizers. However, in the liquid fertilizers presently in wide use, these trace elements precipitate out of solution because the liquids are neutral or basic in nature. The liquid fertilizers of the present invention are highly acidic and are non-ammoniated liquid fertilizers, rendering trace elements more soluble.

Potash, potassium chloride, is soluble in reasonable proportions, i.e., up to about 20 weight percent; however, the so called super concentrations of potash are obtained by suspending the potash beyond its solubility limits in a finely divided form with the aid of gelling materials such as clays (montmorillonite, bentonite, heteropolysaccha rides, natural gums and the like). The gelling material is present in a viscosifying amount sufficient to suspend finely divided solid particles, e.g., 50 to 1000 30 microns.

The reaction of phosphoric acid and urea is exothermic; however, it proceeds at a rather slow rate. This reaction rate can be increased and sulfur can be added to the fertilizer composition by employing mixtures of phosphoric acid and sulfuric acid; preferably from 5 up to about 80 weight percent of the total acid content may be sulfuric acid, more preferably up to about 50 weight percent. 35 The compositions of the present invention may be further characterized as having total N, P20r, and K20 analysis of at least 25 weight percent and preferably greater than 30 weight percent of the fertilizer. It should be appreciated that only N and P205 may be present in some compositions and that the total analysis characterizing the composition is based on these two components, K20 being 0.

The first feature of the products of this invention that contributes to improved agronomic efficiency is the lowering of soil pH locally, which substantially improves the availability and mobility of metallic trace elements. This effect is well known; it has been used in the past to increase trace element availability, but not in the form of this invention, employing acid fertilizers.

A second factor of unique importance in the enhancement of agronomic efficiency is the protective effect of sulfuric acid on the mobility of phosphate ions in the soil. In many instances, calcium ions are present in the soil in a form and to a degree that lead to the formation of insoluble calcium phosphate. This is substantially phosphate rock, similar to that from which the phosphate was originally freed by the action of sulfuric acid. Sulfuric acid in the formulations of this invention will achieve the same effect, tying up calcium preferentially as insoluble calcium sulfate while the phosphate remains free and available.

A third element in the improvement of agronomic efficiency relates to the retention of nitrogen in the soil. The loss of nitrogen as ammonia to the atmosphere is a well known phenomenon in agriculture, and one of the advantages of urea over ammonia is that this loss is greatly reduced. However, urea is converted to ammonia by decomposition in the soil in an essential first step toward ultimate utilization by plants; in this process, ammonia will still be lost to the atmosphere. The acid fertilizers of this invention delay and reduce this loss by at least two mechanisms. First, the hydrolysis of urea and conversion to ammonia is slowed by the fact that it is present as an acid reaction product. Beyond this, the acid environment created by the use of the products of this invention provides sites to which ammonia is strongly attached as soon as it is formed; as a result, the loss of ammonia into the atmosphere is substantially reduced. This is a factor of considerable agronomic significance.

The present invention will be further described by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a binary graph of OOC stable urea-phosphoric acid composition.

Fig. 2 is a ternary graph of OOC stable urea-sulfuric acid-phosphoric acid compositions.

Fig. 3 is a graph showing OOC stable urea-phosphoic acid K20 compositions.

3 GB 2 034 682 A The reaction between reagent grade urea and food grade phosphoric acid, 75%, can be conducted to give products of analysis up to 22-28-0 (N-P-K). This is accomplished without added water, by simply stirring the mixture of urea and acid. Heating is mild, the solutions are viscous and the reactions slow, requiring several hours in small batches to reach completion at high N values. If it is desired to increase the ratio of N to P, maintaining good low temperature stability, it is found that this can only be done by reducing the P level by dilution. If water is used as the diluent, the result is as shown in Fig. 1, where it can be seen that actual N concentration falls as the system is diluted.

N-P solutions with sulfur can be made by blending urea-sulfuric acid (USA) with phosphoric acid (PA). These solutions are completely miscible in all proportions, and of good stability if kept covered to exclude atmospheric moisture pick-up. No heating is observed in mixing, but since both liquids are 10 viscous, some agitation is required to produce a uniform blend. In Fig. 2 the line marked... USA-PA" gives the compositions available by this technique.

Because of the high intensity of the urea-sulfuric acid reaction, special procedures are needed to make the concentrated product on a commercial basis. If the desired product requires acid of 50% concentration or less, the urea can be slowly added to the acid with stirring. If however, the acid is 15 stronger than this, decomposition may result if this procedure is followed. In these cases, it is desirable to add the acid slowly to the urea while tumbling; after a fraction of the acid (20-30%, depending on concentration) has been added, a stirrable slurry is formed. Slow addition of the remainder of the acid while stirring brings the system to complete reaction.

Once a batch of liquid product has been made, it can be used as a base for further manufacture. 20 This is done by placing the liquid in a stirred vessel of appropriate size, adding urea in sufficient quantity to double the size of the finished batch, adding any water required for the formulation, and slowly adding the sulfuric acid while stirring. Leaving a heel of liquid in the vessel permits furher manufacture to be conducted in a stirred fluid mass.

N-P solutions with sulfur can also be made by combining urea, sulfuric acid and phosphoric acid 25 directly. To do this, the two acids are measured, combined and mixed; some heat generation accompanies this operation. The urea is then added, with stirring; here the heat release is appreciable, depending on the proportion of sulfuric acid in the mix (higher sulfuric acid content generating more heat). Reaction is rather rapid, generally being complete in 15-20 minutes, again depending somewhat on the proportion of sulfuric acid present. By this method it is possible to combine more 30 urea and phosphoric acid in the product with a given amount of sulfuric acid than can be done by blending phosphoric with pre-reacted urea-sulfuric acid. Fig. 2, line "U- SA-PA" shows the results that can be achieved by this method.

Turning now to the use of field grade materials in the preparation of these compounds, certain limitations arise due to the condition of the urea and/or the composition of the phosphoric acid.

Field grade phosphoric acid generally contains some free sulfuric acid, some dissolved or suspended metal salts, and some organic residues or carbon. Table I gives analysis of some field grade materials. While Food Grade acid of the same strength is water-white, with a specific gravity of 1.574 and a viscosity less than 100 cp at 700F, field acids are highly colored (green, brown or black), with specific gravities ranging from about 1.65 to 1.95 and viscosities are high as 1000 cp. The high values 40 of viscosity and specific gravity indicate the presence of metal salts and sulfuric acid, with correspondingly reduced water content. As a consequence of these compositional variations, some difference in behaviour must be expected when making compounds described above using field acids.

Table 1

Composition of Commercial Phosphoric Acids, Wt% 45 Constituent A 8 c D E P205 54.8 53,4 52.8 53.4 52.1 Ca 0.01 0.1 0.05 0.1 0.03 Fe 0.7 0.8 0.7 1.2 0.5 50- AI 0.7 0.3 0.4 0.6 0.6 50 Mg 0.3 0.2 0.3 0.3 0.2 Cr 0.03 0.01 0.01 0.01 0.04 v 0.04 0.01 0.01 0.02 0.04 Na 0.03 1.9 0.04 0.2 0.1 K 0.07 0.1 0.03 0.01 0.1 55 F 0.7 0.3 0.4 0.9 0.5 S03 3.0 1.8 2.8 1.5 2.2 S'02 0.2 0.2 0.2 0.1 0.1 c 0.1 0.04 0.8 0.2 0.04 Solids 1.7 5.1 8.3 2.9 0.5 60 Filtered, dried 1 hour @220'F.

Source: Encyclopedia of Chemical Technology, 2nd Ed., Vol. 9, p. 88.

4 GB 2 034 682 A 4 Another feature of these field grade acids that will be relevant to their performance in making the fertilizer compounds described is the slow precipitation of a complex iron-aluminum-potassium phosphate. This compound forms continuously until the component in shortest supply is virtually depleted; this is usually potassium. Consequently, when potassium (in the form, say, of potassium chloride solution) is added to such an acid with modest amounts of iron and/or aluminum still present in the acid " further precipitation of the complex salt occurs. The salt, (Fe, A03 KH14(PO4),. 4H20, has about the same phosphate content as the remainder of the acid, so no effect on the assay is noticeable due to the modest amount of insoluble material which might settle out.

In any field situation, it must be presumed that some carbamate is present in the urea; in fact, 10 some carbamate is probably present inmost urea as it is supplied.

In storage, however, further hydrolysis of the urea may occur, particularly under warm wet conditions to produce ammonium carbonate, ammonia and carbon-dioxide; as a result field grade urea is likely to be appreciably different from reagent grade product.

The degradation of urea can be catalyzed by certain metal salts, notably some of these occurring in field grade phosphoric acids. In such cases, carbon dioxide is given off and solid ammonium 15 phosphate is formed. This type of degradation is accelerated by high temperature and low pH.

It is consequently found that with field grade materials it is not generally possible to reproduce fig. 1, although with urea in good condition and certain acids (including furnace grades) the compounds described can be made. Best results with field materials have come with the use of sulfuric acid, phosphoric acid and urea as described above and shown in Fig. 2 (line U-SA-PA). Using this method, it is possible to prepare the compositions shown in Fig. 2 with a wide variety of field acids.

Highest assays and best stability in storage are achieved when the urea is in good condition, that is, when it has undergone little or no hydrolysis. With such urea and a variety of field grade acids, a broad range of N-P-S compositions represented by Fig. 2 (line U-SA-PA) are readily made as shown in

Table 11 which is extracted from Fig. 2.

TABLE 11

N-P solutions with S made with field components

M010 M010 Blend U PA SA N p K S - 1 17.5 74.5 8 8 40 0 2.5 30 2 22 69 9 10 37 0 2.8 3 26 64 10 12 34 0 3.1 4 30 59 11 14 31 0 3.4 35 53 12 16 28 0 3.7 35. 6 39 48 13 18 26 0 4.0 35 7 43.5 41.5 15 20 22 0 4.6 8 48 33.5 18.5 22 18 0 5.7 9 53 24 23 24 13 0 7.1 57 17 26 26 9 0 8.0 U-urea.

PA-phosphoric acid. SA-sulfuric acid.

The N-P liquids described above and illustrated in Fig. 1 and Fig. 2 can be augmented with K to make full N-P-K liquids. One method of producing these materials is to prepare a M solution and blend it with the N-P liquid of choice. It is found, when laboratory materials are used, that for the most part the liquid blend arithmetically; that is, if two liquids of OOC stability are blended in any proportion, the blend will have the same stability. In some regions of composition, somewhat more K can be introduced. This behaviour is shown in Fig. 3, where any composition within the envelope curve can be made; the ends of this curve show the slightly anomalous behaviour referred to above. 50 Fig. 3 represents the compositions shown in Fig. 1 along the abscissa. Compositions between 54 50 and 50% combined N and P are those shown in the right-hand portion of Fig. 1; below 50% N+P on Fig. 3 the N-P blends contain water and follow the compositions shown in the left-hand portion of Fig. 1. A number of these compositions can be made with field grade acids, occasionally an acid is encountered which does not permit making the higher analysis compounds on or near the envelope curve. In most cases, such acids can be used for lower grades. Generally, if the N-P solution can be made with a field acid, so can the appropriate N-P-K solution. One problem that arises with field grade acids is the potash reaction mentioned above, which causes sedimentation. This effect may not rule out the use of a given acid, however, because it does not reach serious proportions immediately and there would normally be time to apply such a mixture; further, the sediment is relatively insoluble in the solution, but would slowly dissolve in the soil solution, so its nutrient value would not be lost. With furnace grade acids this type of reaction does not occur.

Q 4 GB 2 034 682 A 5 To use Fig. 3, select the ratio of N to P desired, and locate along the abscissa the total N-P content permissible where:

N Point P'O' A 5 5 B 3 c 2 D 1 E 0.786 F 0.5 10 G 0.2 Points to the left of line E require water.

From this vallue and the ratio, the composition of the base N-P solution (urea, phosphoric acid and water if indicated) can be found. Blend in solid potash to reach any point along the tie line, within the envelope curve. If a higher potash content is needed, with the same N-P ratio, the solution can be blended with I(C1 solution, generally following the envelope up and to the left; this procedure dilutes the total nutrient content, but maintains the N-P ratio.

The following examples illustrate that claimed as the invention; however, they should not be viewed as restricting the scope of the claims to which the inventor is otherwise entitled. The liquid fertilizers are analyzed and the analysis reported with three or four numbers. The numbers (weight 20 percent) represent the components (n-P20g--K20-S).

- Example 1

To 630 grams of 75% furnace phosphoric acid (Food Grade) 370 grams of urea was added with moderate stirring. Mild heat evolution occurred, and the solution of the urea was complete in 15 minutes. The product was a fluid water-white material of pH 1.5, stable to storage at OOC. Analysis of 25 the product was 17-34-0.

Example 2

435 grams of urea was wetted with 194 grams of water; with brief mild stirring the urea disintegrated into a slurry. To this slurry was added, with moderate stirring, 371 grams of wet process phosphoric acid, 54% P205 Mild warming occurred, and the solution was complete in 15 minutes. The 30 product was fluid, clear and stable at OOC. It analyzed 20-20-0. This material was miscible in all proportions with phosphoric acid to give lower nitrogen-phosphate ratios, such as 10-37-0, 5-45.5-0 etc.

Example 3

Sulfuric acid (66 Be) and wet process phosphoric acid (0-54-0) were mixed in the proportions 80 35 to 745 grams, respectively. The mixture was stirred, exhibiting mild warming. While stirring, warm 175 grams of urea was added. Solution was complete within ten minutes. The product was a clear, stable, viscous liquid, with pH of 1.7; it analyzed 8-40-0-2.5S.

Example 4

260 grams of sulfuric acid (66 Be) was mixed with 170 grams of wet process phosphoric acid, 40 54% P20,. To the stirred mixture 570 grams of urea was added. Solution was effected rapidly, within five minutes, giving a clear, stable fluid analyzing 26-9-0-BS.

Example 5

407 grams of urea and 65 grams of potash (potassium chloride) was wetted with 182 grams of water to disintegrate the urea and forma heavy slurry. This was stirred slowly for a few minutes to 45 complete the action, and 346 grams of wet process phosphoric acid, 54% P, Or,, was added. After stirring for 15 minutes the solution was clear, fluid and free of undissolved material. It stored well at low temperatures, down to -70C, for extended periods; at room temperatures of 24-271C some crystals of potash started to appear after two weeks. Analysis of this product was 18.7-18.7-4.

Example 6

The product of Example 5 was mixed with additional wet process phosphoric acid in the ratio of 591 grams to 409 grams. With very mild stirring the mixture was completed in a few minutes to give a clear, fluid stable product analyzing 11-33-2.4. It was found that other ratios, such as 13.9-27.8-3, 9.2-36.8-2 and 7.8-39-1.7 could be made with equal ease.

Example 7

To 249 grams of water was added 97 grams of potash with good stirring. The solution becomes 551 6 GB 2 034 682 A very cold and the potash normally dissolves very slowly; however, after a few minutes of agitation 267 grams of wet process phosphoric acid was added. The heat of dilution of the acid aided the solution of the potash, and within a few minutes it was in solution. 387 grams of the product of Example 5 was then added, and stirring was continued for ten minutes. The resulting solution was fluid and stable, analyzing 7.2-21.6-6.

Example 8

653 grams of urea was placed in a beaker and moistened with 20 grams of water while slowly stirring. To this mass was added 327 grams of commercial 66 Be sulfuric acid in the following manner: Acid was added slowly with slow agitation until approximately 15% of the addition was completed. At this point the mass had liquified into a mixable slurry and the speed of agitation was increased to a mild level. Slow addition of acid was continued until all the acid was incorporated into the mass. Stirring was continued for a few minutes, then stopped while the material cooled and entrained air escaped. The product was a viscous, water-white liquid analyzing 30-0-0-1 OS, with a pH of 1.5; on dilution with water no heat was evolved.

Example 9

A mixture was made of 445 grams of the product of Example 5 with 555 grams of the product of Example 8. Simple stirflng of the two viscous liquids for a few minutes was sufficient to effect complete solution. The resulting fluid fertilizer analyzed 25-8.3-1.8-5.5S.

x Example 10

A suspension fertilizer was made by pregelling 15 grams of attapulgite with 120 grams of wet 20 process phosphoric acid. To this was added 308 grams of urea-sulfuric acid, the product of Example 13; following this addition, 65 grams of wet process phosphoric acid was incorporated. Potash in the amount of 492 grams was then blended into the mixture. The resulting suspension analysed 9-10-30 3S.

Example 11 25

A mixture of 306 grams of the product of Example 8 and 278 grams of wet process phosphoric acid was made by thorough mixing for a few minutes. Into this mixture was incorporated 6 grams of Xanthan gum with thorough mixing for 10 minutes, until gellation began to occur. At this point, 410 grams of potash was blended in, and mixing continued for an additional 10 minutes. The fluid suspension thus prepared analyzed 9-1 5-25-3S.

Example 12

To illustrate the effect of low pH fertilizers on sofl, four soils, ranging in character from sandy through fine sandy loam to clay loam, were treated with a solution of urea in water. Duplicate samples of each soil were also treated with the reaction product of urea and sulfuric acid, the product of Example 8. In each case, the level of nitrogen added to the soil was 280 mg. The soil samples were so 35 arranged that nitrogen lost from the surface to the atmosphere as ammonia was continuously collected and monitored. The results of these experiments are tabulated below, giving loss measurements made at 72 and 168 hours.

Nitrogen Loss From Surface, Mg 40 Soil Type joH Treatment 72 hrs 168 hrs A Clay Loam 6.85 Urea/Water 10 93 Urea/Acid 2.5 10 B Sand 5.1 Urea/Water 163 275 Urea/Acid 4 4 45 c Clay Loam 4.95 Urea/Water 30 81 Urea/Acid 0 7 D Fine Sandy 5.2 Urea/Water 121 200 Loam Urea/Acid 1 2.5 Note that from urea/water the nitrogen losses in one week are a very large part of the material added.

The decompositions of urea and loss of ammonia to the atmosphere is greatly delayed and reduced in soils of agricultural significance by acid compositions such as those according to this invention. The importance of this property of the products of this invention is very substantial.

Claims

Claims 1. A high analysis, liquid fertilizer composition comprising the reaction product of urea and phosphoric acid, and having a pH of less than 4.

1 7 GB

2 034 682 A 7 2. The fertilizer composition according to Claim 1 wherein said pH is in the range of 1.5 to 4.

3. The fertilizer composition according to Claim 1 wherein said pH is less than 2.

4. The fertilizer composition according to Claim 1 further characterized as being clear and being stable against salting out at OIC.

5. The fertilizer composition according to Claim 1 wherein potash is present as a component. 5

6. The fertilizer composition according to Claim 5 wherein said total analysis of N, P105 and K,O is at least 25 weight percent.

7. The fertilizer composition according to Claim 5 wherein said total analysis of N, P105 and K20 is at least 30 weight percent.

8. The fertilizer composition according to Claim 1 wherein the reaction product of urea and 10 sulfuric acid is additionally present, said sulfuric acid content being up to about 80 weight percent of the total acid content of said fertilizer composition.

9. The fertilizer composition according to Claim 8 wherein said sulfuric acid is up to about 50 weight percent of the total acid content of said fertilizer composition.

10. The fertilizer composition according to Claim 1 wherein a viscosifying amount of a viscosifying agent is present for suspending finely divided solid particles.

11. Th6 fertilizer composition according to Claim 10 wherein potash is present in excess of its solubility in said composition, as a finely divided solid.

12. A process for preparing a high analysis, liquid fertilizer composition containing nitrogen and phosphorus in a weight ratio of N:P205 of 0.6:1 or more comprising adding phosphoric acid to urea, 20 mixing said material and allowing said phosphoric acid and urea to react autothermally and recovering a liquid product being stable against salt out at OIC.

13. The process according to Claim 12 wherein said urea is dampened or slurried with water priol to phosphoric acid addition.

14. A process for preparing a high analysis, liquid fertilizer composition containing nitrogen, 25 phosphorus and sulfur comprising mixing from 5 to 80 weight percent sulfuric acid with phosphoric acid, based on said phosphoric acid, adding urea thereto, mixing said materials, allowing said acids and urea to react autothermally, and recovering a liquid product which is stable against salt out at OIC.

15. A process for preparing a high analysis, liquid fertilizer composition containing nitrogen, phosphorus and sulfur comprising reacting urea and sulfuric acid autothermally, admixing phosphoric 30 acid therewith and recovering a liquid product which is stable against salt out at OOC.

16. A fertilizer composition as claimed in Claim 1 substantially as hereinbefore described in any one of the Examples.

17. A process of producing a fertilizer composition as claimed in Claim 12 substantially as hereinbefore described in any one of Examples 1, 2, 5, 6, 7, 9, 10 and 11.

18. A process of producing a fertilizer composition as claimed in Claim 14 substantially as hereinbefore described in any one of Examples 3 and 4.

19. A process of producing a fertilizer composition as claimed in Claim 15 substantially as 40hereinbefore described in any one of Examples 8, 9, 10 and 11 - 19.

20. A fertilizer when produced by a process as claimed in any one of the preceding claims.

2 1. A fertilizer as claimed in Claim 1 substantially as hereinbefore described in any one of the Examples.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1980. Published by the Patent Office.

Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

0

20. A fertilizer when produced by a process as claimed in any one of Claims 12 to 15 and 17 to 40 New Claims filed on 31.1.80. Superseded Claims 1-20.

New or Amended Claims:

1. A high analysis, liquid fertilizer which is the reaction product of urea and phosphoric acid or a 45 mixture of phosphoric acid and sulfuric acid, is a clear liquid which is stable against salt out at O'C, has a pH of less than 4, and contains N and P20 and optionally K20, the analysis of N, P20. and K20 totalling at least 25 weight percent of the fertilizer.

2. A fertilizer composition as claimed in Claim 1 wherein said pH is in the range of 1.5 to 4.

3. A fertilizer composition as claimed in Claim 1 wherein said pH is less than 2.

4. A fertilizer composition as claimed in Claim 3 wherein said total analysis of N, P20., and K20 is at least 30 weight percent.

5. A fertilizer composition as claimed in any one of the preceding claims wherein the mole ratio of the urea:acid is at least 1:1.

6. A fertilizer composition according to Claim 1 wherein the reaction product of urea and sulfuric 55 acid is additionally present, said sulfuric acid content being up to 80 weight percent of the total acid content of said fertilizer composition.

7. A fertilizer composition as claimed in Claim 6 wherein said sulfuric acid is up to 50 weight percent of the total acid content of said fertilizer composition.

8. A fertilizer composition as claimed in any one of the preceding claims wherein a viscosifying 60 amount of a viscosifying agent is present for suspending finely divided solid particles.

9. A fertilizer composition as claimed in any one of the preceding claims wherein potash is present in excess of its solubility in said composition, as a fine divided solid.

8 GB 2 034 682 A 8 10. A process for preparing a high analysis, liquid fertilizer composition consisting essentially of:

1) admixing; urea and phosphoric acid of up to 75% H,PO, in a mole ratio of up to 2 moles of urea per mole of acid present, or urea and a mixture of phosphoric acid of up to 75% H3PO, and from 5 to 80 weight percent 5 suffuric acid based on said phosphoric acid in a mole ratio of up to 3 moles of urea per mole of acid present; 2) reacting said urea and said acid exothermally and without external heating; and 3) recovering a liquid product having a total N, P,O, and K,0 analysis of at least 25 weight%, a pH in the range of 1.5 to 4 and which is stable against salt out at OOC.

11. A process as claimed in Claim 10 wherein the ratio of at least 1 mole of urea per mole of acid is present.

12. A process as claimed in Claim 10 or Claim 11 wherein the product has a total analysis of N, P201 and K,0 at least 30 weight percent.

13. A process as claimed in any one of Claims 10 to 12 comprising adding phosphoric acid to urea, mixing said materials and allowing said phosphoric acid and urea to react to form a fertilizer composition containing nitrogen and phosphorus in a weight ratio of N:P,O, of 0.6 or moreA.

14. A process as claimed in Claim 13 wherein the urea is dampened or slurried with water prior to phosphoric acid addition.

15. A process as claimed in Claim 10 or Claim 11 comprising mixing from 5 to 80 weight percent 20 sulfuric acid with phosphoric acid, based on said phosphoric acid, adding urea thereto, mixing said materials, and allowing said acids and urea to react; to form a fertilizer composition containing nitrogen, phosphorus and sulphur.

16. A process as claimed in Claim 15 wherein said sulfuric acid is up to 50 weight percent of the total acid content of said fertilizer composition.

17. A process as claimed in any one of the preceding claims wherein viscosifying amount of viscosifying agent is present for suspending finely divided solid particles.

18. A process as claimed in any one of the preceding claims wherein potash is present in excess of its solubility in said composition, as a finely divided solid.

19. A process of producing a fertilizer composition as claimed in Claim 11 substantially as 30 hereinbefore described in any one of the Examples.