IL30335A - A mineral feed supplement and process and apparatus for the manufacture thereof - Google Patents

Description

mis"'? A MINERAL TEED SUPPLEMENT AND PROCESS AND APPARATUS FOR THE MANUFACTURE THEREOF GUANO-WBRKE AS (vorm. Ohlendorff'sohe und Merck* aohe Werke) 0:28602 The present invention relates to mineral feed supplements for farm livestock or animals and to methods and apparatus for making such supplements. ' High performance farm livestock is not only subject to deficiencies of phosphorus and calcium but also of sodium, magnesium and the trace elements iron, copper, manganese, ' •cobalt and zinc. In contrast to phosphorus, calcium is generally present in the basic fodder or feed in a sufficient quantity and may often be present in excess. Since cal' cium is only excreted as calcium phosphate from the body, if there is an excess of calcium in the feed the livestock is liable to phosphate deficiency. For this reason high quality mineral, feed mixtures for cattle should contain a Ca:^* ratio which is less than 1:1.

One object of the present invention is the provision of a high quality feed supplement which takes the above considerations into account. The invention is more specifically concerned with a method for the production of a mineral feed supplement by reacting a mixture containing sodium, magnesium and possibly also calcium compounds with phosphoric acid.

A process has already been previously proposed for producing a mineral feed supplement by simultaneous. neutralisation of a phosphoric acid with a ?2 5 C OIlt ent o f 40 to 60 % with the oxides, hydroxides or carbonates of sodium, magnesium and possibly also of calcium, cooling and drying of the product, preferably with a recycling of the coarse and very fine fractions into the neutralisation part of the process after these fractions have been separated by screening.

The feed supplement of this previously proposed process contains as its substantial component a complex phosphate mixture whose composition corresponds with the following monohydrogen phosphate quantities, expressed as moles percent: disodium hydrogen phosphate 25 - 60 magnesium hydrogen phosphate 20 - 50 calcium hydrogen phosphate 0 - 25 In contrast to other methods, in this previously proposed method, the phosphates of sodium, magnesium and pos-. sibly also of calcium intended for the feed supplement we-re obtained in a single working operation, that is to say substantially in a single process stage, by simultaneous neutralisation of oxides, hydroxides or carbonates of the 3 elements intimately mixed in a form of a complex monohydrogen phosphate mixture. One further object of the pre-sent invention is to provide a process which represents an improvement over this previously proposed process.

Another previously proposed method was adapted to include, on the one hand, the use of numerous materials which are of no interest as far as the present invention is Conor cerned, such as natural f synthetic silicates, aluminium compounds, and /or bone feed meal as essential components, while on the other hand, in the previously proposed p.rocess, substances which are essential for the carrying out of the present invention, more especially sodium and possibly also calcium cannot/ used in the form of oxides, hydroxides or carbonates which were specifically stated not to be applicable, and instead the sodium, for example, was used primarily in the form of chloride and the calcium was used in the form of the phosphate.

The present invention is also not rendered obvious by the step in another previously proposed process of adding a dolomite in an amount which was 50 % greater than would in accordance with the present invention it is in fact the di-stage which is aimed at. As a result of this stipulation in ' the previously proposed method, which did not propose the use of any alkali addition, the dough-like pro- duct had to he subjected to a further drying operation. On the other hand the product in accordance with the invention is produced in a practically dry state, especially as the recycling of the coarse and finest fractions of the product into the neutralisation part of the process counteracts the formation of dough-like or semi-liquid masses.

In accordance with another previously proposed method, for the production of a fertilizer, chalk is reacted with metaphosphoric acid in the presence of steam either at temperatures of 110 to 120° C with the formation of water-so-luble primary calcium orthophosphate, or at temperatures between 400 and 600° C to form water-insoluble calcium metaphosphate, it being possible to convert the calcium metaphosphate into primary calcium orthophosphate by subsequent treatment with steam.

In the carrying out of the method mentioned initially on a industrial scale some :. improvements have been discovered which form the subject matter of the present invention. , that is to sodium hy- , the mix- ture passes through a semi-liquid phase, in which strong heating takes place, and this semi-liquid stage leads to a considerable increase in the power required for opera-ting the mixing parts of the mixing apparatus. Although it is true that this great increase in power requirement can be considerably reduced and made of shorter duration b the recycling of fines and comminuted particles of excessive size, this measure still entails the use of sub- stantially. strong designs. of mixer and more powerful drive motors.

The present invention consists in a met¾od for the production of a mineral feed supplement comprising the neutralisation in a neutralisation zone of a phosphoric acid having 'a P205 content of 40 - 60 % hy weight with a mixture of sodium and magnesium, and possihly also calcium^, in the form of oxides, hydroxides or carbonates, cooling, and drying the product, preferably with a sieving off and recycling of fine and coarse fractions to the neutralisation zone, characterised in that the mixing of the mixture with the phosphoric acid takes place in a mixing drum rotating about a generally horizontal axis provided with lifting vanes which cause fine solid particles in the mixture to cascade down in a shower and the phosphoric acid, and possibly also sodium hydroxide solution, is or are sprayed into the shower so as to react with the particles in it.

The mixture of solid reactants comprising oxides, hydroxides or carbonates and if desired also recycled material from the sieving step, can conveniently be introduced at one end of the mixing drum by means of a chute, and forms a thick cascading shower which is evenly distributed across the cross-section of the rotating drum„ The phosphoric acid and sodium hydroxide solution, if used, are introduced using suitable spray nozzles. In reaction there is a considerably development of heat and the resulting reaction gases, that is to say, steam, and possibly carbon dioxide, are removed by means of an extractor fan at the outlet end of the drum. With this manner of operation a moist friable crumb in a partially granulated condition is produced from through a semi-liquid or viscid phase. The fresh material produced in this manner is then preferably cooled in a cooling drum wit the hel of fresh air blown i so that physically held water is removed, at least partially, from the. product. The/product is then preferably sieved by means o a following sifting installation into a main fraction, preferably in the size range 0.5 to 2 mm, overrSize, that is to say coarse, particles, and under-slze, that is to. say fine , particles.

The coarse particle fraction separated by sieving from the product;; of a preceding operation is apt still o be in a more or. less plastic condition, mainly because the larger particles in i are, possibly not fully cooled in the air current. This condition gives sometimes rise to difficulties in the recycling of the ooarse fraction to the reaction or neutralisation zone, particularly as the particles may conglomerate in a grinder or toill provided for. size reductio , Where such plastic condition of the product occurs, the ■ aforesaid difficulties can be avoided, by an optional feature ^ of the invention, in that the sieved«-off coarse fraction is ■ mixed with a fresh solid reaction component before being introduced into the grinder, or that in the latter a mixture of the coar fraction with the fresh componen is ground.

Although the monbhydrogen phosphate mixture as produced by the method in accordance with the present invention are sufficiently free of moisture to be dry and free-flowing owing to the evaporation of water during the reaction of the compprients in the mixing drum and, preferably, in a following cooling drum, they contain more or less substantial amounts of water of crystallisation, in accordance with the concentrations of the phosphoric acid and sodium hydroxide solution. It has been found in ract ce that if the hos hate mxture i stored In temperatures during transport, there may he a conglomeration of the particles leading to the formation of lumps ,so that ,further handling or treatment of the material is. made difficult.

This tendency to form lumps can he counteracted if the material is treated with suitable anti-agglomerating agents such as calcium or magnesium stearate in the form of powder.

However a further possibility for completely preven-ting agglomeration or lump formation, forming a particular feature of the present invention, is to heat the product so as to hring about a more or less complete removal of water of crystallisation. This removal can be brought about in a drying drum following mixing in the mixing drum. For instance the cooling air used can be heated to 50 to 100° G so as to exert a drying action for removal of the water of crystallisation.

It is also possible to feed the freshly prepared material leaving the mixing drum on to a belt dryer in order to free the material of its water of crystallisation and other water contained in it. The dry material leaving the belt dryer is then fed to a grinding means to reduce it to the desired particle size. In the case of the preparation of a granulated product the under-size and over-size mate-rial is then preferably returned to an earlier stage in the production process.

In accordance with a further aspect, the present invention also consists in an apparatus for making a mineral feed supplement comprising a drum arranged to rotate about the generally horizontal axis, means feeding a mixture of sodium and magnesium in the form of oxides, hydroxides or carbonates into the drum, vanes inside the drum for lifting the mixture inside the drum and causing it to cascade ' downwards in a shower, means for spraying a phosphoric acid into the drum, and means for cooling the mixture on leaving the drum, In accordance with a still further aspect the present invention consists in a mineral feed supplement containing as a substantial component a complex phosphate mixture containing the following moles percent of monohydrogen phosphates disodium hydrogen phosphate 25 - 60 magnesium hydrogen phosphate 20 - 50 calcium hydrogen phosphate 0 - 25 The invention will now be further described with reference to two specific examples.

Example 1 3000 kg recycled under-size fraction (below 0.5 mm) and recycled over-size fraction (above 2.0 mm), 1070 kg sodium carbonate of 98 % purity and 650 kg dolomite hydrate, containing 42.5 % CaO by weight and 30,6 % MgO by weight, were continuously ground per hour. The finely comminuted mixture of over-size and under-size fractions and the solid reac tion component was then passed into a reaction drum rotating about a horizontal axis and having a length of 5 met-res and a diameter of 2 metres. The drum was provided with lifting vanes so that on rotation the mixture was caused to cascade downwards in a shower which was even in cross-section and in longitudinal section.

Into the shower 3110 kg phosphoric acid containing 45 % PgOg was sprayed per hour after being heated to 70° C in a heat exchanger.

Owing to the heat of reaction about 375 kg water were steam arid carbon dioxide, together with air drum into the drum,, were drawn, off out of the drum 'by means of an extraction fan.

The hot material in the form of friable crumb lea-ving reaction drum was passed into a cooling drum of 8 me-tres in length and 2 metres in diameter which was also provided with lifting vanes, i.e. internal structures for causing the material to cascade. In this cooling drum the material was cooled by counter-current air. > -· The cooled material which had simultaneously been freed of accompanying water,was then classified by means of vibra-to'rary sieves. Under-size particles below 0,5 mm and oversize particles above 2.0 mm were returned to an earlier stage in the process.

The rate of production was 4000 kg per hour of a feed supplement ready for use having the following analysis: .0 % P205 (15":5 % P), 6.9 % CaO, 5.0 % MgO, 15.3 % Na20 (all percentages being by weight).

Example 2 The process described in example 1 was operated in substantially the same manner but there was the modification that sodium hydroxide solution was used instead of sodium carbonate and for the purpose of removing water of crystal-lisation heated air was passed through the cooling drum.

Per hour 4000 kg recycled material with the water of crystallisation removed by heating and 650 kg dolomite lime hydrate,,. containing 42.5 % CaO by weight and .6 % MgO by weight, were ground together and passed in-to the reaction drum. Into the cascading shower of solid particles 2500 kg phosphoric acid containing 56 % PgOg by weight and 1580 kg sodium hydroxide containing 50 % by weight NaOH were injected continuously. The phosphoric acid and hydroxide solutions were heated to 60° C by continuous flow heaters. The quantity of heat produced by the neutralisation led to the formation of steam which was removed by an extraction fan.

The freshly produced material was then heated to remove water of crystallisation using the same drum as used in example 1, air heated by means of an oil burner being drawn through the drum for this purpose together with air directly from the atmosphere. The degree of removal of water of crystallisation desired was regulated by regulation of the temperature, for example between 50° C and 100° C or above, or by regulating the quantity of hot air passing through the drum.

The dried material was cooled and classified as. was the case with example 1. The weight of production per hour was 3500 kg finished material and 4000 kg over-size particles, under-size particles, and dust, which had to be recycled.

The analysis, by weight, of the finished product was as follows: 40.0 % P2°5 7e9 °/° Ga0 5.7 % MgO 17.5 % Na 0 c The invention will now be further described with reference to the accompanying drawings.

Figure 1' is a flow diagram showing the production of a mineral animal feed supplement in accordance with the me-thod of the invention.

Figure 2 is an end view of a reaction and mixing drum used in the method in accordance with the invention.

Figure 3 is a cross-section through the drum shown in figure 2.

Figure 4 is a side view of the drum shown in figure 2.

Figure 5 is a plan view and partial section of the drum 1 phosphoric acid is supplied through line 1 and fed at a controlled rate while sodium hydroxide is supplied through a line 2 and fed at a measured rate. A supply container for sodium carbonate is denoted hy reference numeral 3 while reference numerals 4 and 5 respectively indicate supply containers for magnesite and/or dolomite hydrate, and for ' communited over-size particles together with tin-size particles and dust.

The reaction and mixing drum 6 is provided with lif-ting vanes 8 (see also figures 3 and 5). The solid mater-ials are fed in via the chute 7 to the reaction and mixing drum 6. The liquid component, that is to say phosphoric acid delivered through line 1 with, or without sodium hydroxide solution delivered through line 2 is sprayed by means of one or more spray nozzles 9 into the reaction and mixing drum 6.

The cooling and drying drum 10 and 11 are connected with a fresh air supply line 12. Reference numeral 18 indicates means for warming the air and can for in-stance he in the form of an oil burner.

The material leaving the cooling and drying drum 10 and 11 is supplied to a following sieving installation 13 which can for example comprise vibratory sieves serving for the splitting up of the material into a correct size category 14, over-size particles 15 and under-size particles 16.

The milling means for treating mixed over-sized and under-sized particles is denoted by reference numeral 17 and from it the. ground material passes via the chute 7 into the reaction and mixing drum 6.

The metering devices for solid materials are denoted by reference numeral 20. They can for instance he in the form of belt-type weighing means. The heating devices for the phosphoric acid and sodium hydroxide are denoted hy reference numeral 21, The fume extractor fan 22 serves for removing reaction gases such as steam and COg.

For the mixing of the starting materials, phosphoric acid obtained via line 1, sodium carbonate obtained from container 3, or sodium hydroxide obtained via line 2, and magnesite or dolomite hydrate obtained from container 4, the materials passes through the drum 6 rotating about a horizontal axis which is provided with lifting vanes. These vanes cause the materials to cascade downwards, see figure 3, in a dense shower which is distributed across the cross-section of the drum. The solid components react with phosphoric acid and/ the sodium hydroxide solution, if used, and in consequence a large amount of heat is released which leads to the evolution of gases, that is to say steam and possibly carbon dioxide, which, as mentioned above, are re-moved from the drum by the extractor fan 22 at the end of the drum. A moist friable crumb results which is partially granulated without any semi-liquid or or viscous phase being involved. The freshly prepared material in then fed to the cooling drum 10, 11 in which it is cooled by means of atmospheric air supplied along line 12 so that the. material is freed of physically held water. The material is then fed to the sieving installation 13 which divides it up into the satisfactory category 14, preferably 0.5 to 2 mm in size, and under-sized and over-sized granules, 15 and 16.

In this manner of operation it has been found that the over-sized granules may be more or less plastic because coonot have been com lete. This plastic condition of the granules may lead to agglomeration in the milling means. It has now been found in practical operation that this difficulty can be completely avoided if the solid reaction components were mixed with at least one of the fresh reaction components before being ground in the grinding means 17. In the flow diagram forming figure 1 of the drawings, the over-sized and under-sized particles are shown as being mixed with the soda from the supply container 3 and the magnesite and/or dolomite hydrate from the supply container 4.

Dust is removed from the target size granules by passing them through further drum 10 through which air is passed. Dust is removed from air leaving the drum 10 by suitable also deals with dust-laden air from the sieving installation.

Claims (11)

What We Claim is

1. A process for the production of a mineral feed supplement comprising the simultaneous neutralisation in a neutralisation zone of a phosphoric acid having a I*205 5 content of 40 - 60 % with a mixture of sodium and magnesium in the form of oxides, hydroxides, or carbonates, cooling, and drying the product, characterised in that mixing of the mixture with the phosphoric acid takes place in a mixing drum rotating about a generally horizontal axis 10 provided with lifting vanes which cause fine solid particles in the mixture to cascade down in a shower and the phosphoric acid is sprayed into the shower so as to react with the particles in it.

2. A process in accordance with claim 1 in which the 15 mixture contains calcium carbonate, oxide, or hydroxide.

3. A method in accordance with claim 1 or claim 2 in which coarse and fine particles are sieved off from the product and recycled into the neutralisation zone.

4. A process in accordance with anyone proceeding claim 20 in which sodium hydroxide solution is sprayed into the neutralisation zone in addition to the phosphoric acid.

5. A process in accordance with claim 3 in wfeich/sie- ved-off coarse fraction is mixed with a fresh solid reac^ tion component before introduction into a grinding means 25 for grinding with the component.

6. A method in accordance with anyone proceeding claim i which the product is heated to remove a water of crystallisation, at least to a major extent.

7. A process in accordance with claim 6 in which, the 30 removal of water of crystallisation takes place in a cod- ling; drum by using cooling air at a raised temperature,

8. 1is described above in example 1.

9. A process in accordance with claim 1 substantially is described above in example 2.

10. , An apparatus for making a mineral feed supplement comprising a* drum arranged to rotate about the generally horizontal axis, means feeding a mixture of sodium and magnesium in the form of oxides, hydroxides or carbonates into the. drum, vanes inside the drum for lifting the mixture inside the drum and causing it to cascade downwards in a shower, means for spraying a phosphoric acid into the drum, and means for coolin the mixture on leaving the drum.

11. A mineral feed supplement containing as substantial component a complex phosphate mixture whose composition is as follows: disodium hydrogen phosphate 25 - 60 moles percent magnesium hydrogen phosphate 20 - 50 moles percent calcium hydrogen phosphate 0 - 25 moles percent produced in accordance with the method as claimed in anyone of claims 1 to 9,