DE1592678A1 - Process for the production of phosphatic fertilizers - Google Patents

Description

IBERLIN 33 '8 "MUNICH

Auguste-Viktoria-Strasse 85 Df.- ItIO. HANS RUSCHKE Pienzenauer Strasse 2

Pat. Dr. Ruschke ° patient attorney Agular

Telephone: 0311 / «™ D. _P l.-lng. HEINZ AGULAR Telephone: 0811 ««

PATENTANWÄLTE Postal checking account: -

Coins 66277

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Bank for trade and industry bank account: Depositenkasee 32 <t Γ Π ~ k C> * 7 Q Dresdner Bank Berlin 33 15926/8 ^Munich " Teplitzer Strasse 42 · ν - «r ·» -w »« ρ Dep.-Kassel Leopoldstrasse

Account 32 7608 Account 69B15

Telegram address: Telegram address: Quadrature Berlin Quadrature Munich

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International Minerals & Chemical Corporation, Skokie, Illinois, V.St.A.

Process for the production of phosphate-containing fertilizers

This invention relates to phosphatic fertilizers and, more particularly, to the suppression of fluorine-containing exhaust gases during the manufacture of phosphatic fertilizers. The process of this invention is particularly useful in the manufacture of superphosphates.

Many inorganic acids, such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, chlorosulfonic acid, and various combinations thereof, have been proposed and used for the treatment of phosphatic rock in order to make the phosphate content thereof available as fertilizer. The phosphate content of phosphate-like rock is around 30 to 36 96 P ₂ Oe, ie "66 to 79 bone phosphate of lime (BPL)".

The term "Superphosphai" as it is used in fertilizers

Telindustrie, "refers to various materials which are formed when sulfuric acid, phosphoric acid or a mixture thereof is reacted with phosphatic rock. Normal superphosphate is a material which contains up to about 22 <fc available P ₀ Oc This material is sometimes referred to as "regular,""common," or "simple" superphosphate. Superphosphates containing about $ 22 to $ 40 available PO5 are called "enriched" superphosphates. Triple superphosphate, sometimes "triple" or Denoted "double" superphosphate, usually contains about 40 to 48 $ available ϊ ^ δ * Anhydrous superphosphate or highly analytically pure triple superphosphate, which is generally made from superphosphoric acid, contains up to about 55% available P ₂ Oc.

Triple superphosphate can also be used as an intermediate in the manufacture of a phosphatic fertilizer material. In US Patent 3,212,874 a method is disclosed in which Triple superphosphate mixed with phosphoric acid and the mixture is burned in the presence of steam at a temperature of about 177 ° to 288 ⁰ O to make a HOOH analysinreines phosphate fertilizers.

The mineral phosphates of all commercially exploited natural deposits in the United States and

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Most other countries also contain fluorine and other impurities. The amount of fluorine in phosphate rock varies depending on the area in which the rock occurs. For example, Florida contains phosphate rock usually about. 3.5 "to 4.0 # fluorine. It is believed that the major fluorine constituent of phosphate rock in the United States is calcium fluorophosphate, or fluoroapatite, and that something Fluorine also occurs as calcium fluoride.

Most of the fluorine in the phosphate rock (and the fluorine in phosphoric acid from the so-called "wet process" when used to make a phosphate fertilizer is used) remains in the fertilizer product. It is believed that the fluorine in the superphosphate exists in several forms, such as residual calcium fluorophosphate or fluoroapatite and perhaps as calcium fluoride, calcium silicofluoride, hydrofluorosilicic acid and hydrogen fluoride. However, a significant amount of the fluorine is still used during various stages of the process Fertilizer manufacture developed e.g. during the acidification and digestion steps. The fluorine is in the form of Hydrofluorosilicic acid or, under certain conditions, released as silicon tetrafluoride. The amounts of fluorine developed vary with the type of process used, the origin of the rock and equipment used, and Methods.

The release of fluorine compounds during the

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Acidification step, where relatively concentrated gases, which can be filtered economically will. A significant amount of fluorine escapes from digestion equipment during large scale operations. This is highly undesirable from the point of view of air pollution · » So far, the only method that had been used was to measure the amount of water from the digestion equipment To limit released fluorine to a minimum, in the digestion systems with expensive flue systems to provide.

Each of the present invention has been found to reduce the amount of fluorine normally used during manufacture of phosphatic fertilizers by treating a fluorine-containing phosphatic material, e.g. a phosphate rock, is released with an inorganic acid, by adding an alkali metal or alkaline earth metal compound, which is soluble in the acidified mixture to the acidified mixture, i.e. to the acidic phosphatic Material mixture, can be significantly reduced. Without thereby restricting the invention in any way, it is believed that the alkali metal or alkaline earth metal compounds dissociate in the acidic medium and the corresponding alkali metal or alkaline earth metal ions result, which chemically with the fluorine and silicon in the acidified mixture to form the sparingly soluble

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Combine Silicofluoride. The formation of the alkali metal or Alkaline earth metal silicofluoride leads to a reduction in the fluorine concentration of the aqueous phase, which is the dated Partial pressure exerted by fluorine in the vapors emerging from the reaction mixture is reduced. This in turn continues the amount of fluorine per unit of gas volume resulting from the Reaction mass is developed during the manufacturing steps.

Another important benefit resulting from the addition of the alkali metal or alkaline earth metal compound in accordance with this invention is that the handling properties of the phosphate fertilizer product are improved. To illustrate, "Green superphosphate can be handled as if it were drier than the superphosphate normally, although the free moisture content is similar ; the material is less sticky than the ordinary product when the free acid content is the same, and the dried superphosphate becomes nourishing not as firm to storage drying as the ordinary product, so that it is easier to use. In addition, the production of granulated superphosphate from the partially dried continuously expelled superphosphate product of this invention is also improved because the partially dried superphosphate breaks into more evenly granular particles, with a greater percentage

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of particles which are within the desired "mesh size" than those without the addition of the alkali metal or alkaline earth metal, and handling properties the digestible, continuously expelled superphosphate and the granular product are both improved. Yet another benefit is that the suppression of fluorine-containing exhaust gases reduces corrosion problems will.

It is therefore primarily an object of this invention to provide an improved method of manufacture To convey phosphate-based fertilizer materials.

Another object of this invention is to provide a method for reducing fluorine-containing gases which during the manufacture of phosphate-containing materials by mixing a fluorine-containing phosphatic material be developed with an inorganic acid to convey.

Another object of this invention is to provide a method by which air pollution during the manufacture of superphosphate materials by acidifying a phosphate one on one Minimum size is restricted.

Another object of this invention is to provide an economical method by which the quantities of fluorine-containing gases that are

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ment of superphosphate materials blown into the atmosphere will be "kept to a minimum".

Koch Another object of this invention is a method for improving handling properties a phosphatic fertilizer, which is obtained by mixing a fluorine-containing phosphatic material with a inorganic acid is produced.

These and other objects of the invention are disclosed or described in the following part of the description will.

The process of the present invention is generally applicable to the various processes in which a finely divided, fluorine-containing phosphatic material is mixed with an inorganic acid to produce a solid phosphatic fertilizer at a ^{temperature below about 288 °} C., and normally fluorine-containing gases Thus, the method of the present invention is useful in connection with methods where a material obtained by acidifying a phosphate rock is treated with an inorganic acid, as disclosed in U.S. Patent 3,212,874, but it is special useful in connection with processes in which a phosphate rock is acidified ^{with an inorganic acid at a temperature below about 288 ° C.}

According to this invention, at least one alkali

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metal or alkaline earth metal compound, which in the medium the special inorganic acid dissociates, i.e. the corresponding alkali metal or alkaline earth metal cations results, added to the mixture of the acid and the phosphatic material. Those so formed in the mixture Cations chemically combine with at least a portion of the fluorine content of the mixture and form in the solid phosphatic fertilizer a compound which contains the alkali metal or alkaline earth metal cation and the fluorine. It is believed that this is the corresponding silicon fluoride. The alkali metal or alkaline earth metal compound is added in an amount sufficient to prevent the compound formed by the added cations and fluorine lead to a reduction in the amount of fluorine-containing gases released during the various phases of the Process can be developed, e.g. during the acidification and the drying phase. The result of this in the solid product The compound formed remains in the product.

The inorganic acids used to acidify the phosphate rock for the manufacture of fertilizer materials have been proposed and used and are therefore applicable in the method according to the invention include sulfuric acid, Phosphoric acid, nitric acid, hydrochloric acid, chlorosulfonic acid, and various combinations thereof. The preferred acids are sulfuric acid and phosphorus

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acid, which is used to produce what is known as superphosphates " Phosphate Fertilizers ". The greatest benefits of this invention are obtained when using triple superphosphate is made by acidifying the phosphate rock with phosphoric acid »If triple superphosphate is generally made by wet process acid because of its greater availability and lower cost used. Blast furnace phosphoric acid and a mixture Oven and wet process acid are also useful.

The inorganic acid usually becomes that. Phosphate rock given in an amount sufficient to be reactive with essentially all of the phosphate rock existing compounds can react as there are! dicalcium phosphate, calcium carbonate, fluoroapatite and Calcium fluoride as well as some of the iron and aluminum oxides.

The improvement according to the invention is applicable in several processes for the production of normal superphosphate, for example in the so-called "the" method ( "dan" process), which consists of a number of methods passages, followed by a Lagerungsauf end of several weeks, and in the so-called Davison process, by which a superphosphate is produced, which only requires ten to fourteen layers of storage digestion. These in the process, the product is worfen the Lagerungsaufsohluß under * until the InAgIe iohgewicht conditions Beendig "*"

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the chemical reactions are achieved. The process of the invention is also applicable in the so-called rapid digestion processes for the preparation of both normal and triple superphosphates, such as the process described in US Pat. No. 3,041,158. If the latter type of process does not require storage digestion, which is the case when fluorine evolution is the major problem, then the benefits obtained by using the process of the present invention are not as great as when some other types of processes are used. However, even during the acidification phase, the rapid digestion process of the development of fluorine-containing gases is suppressed. The process according to the invention can also be used in connection with "many other processes which are used for the production of triple superphosphate, for example the" den ¹¹ , Dorr-Oliver and the TVA single-stage granulate processes. Many of these methods are offentlicht in chapters and 8 of the "Chemistry and Technology of Fertilizers"} ^ver "in 1960 by Reinhold Publishing Corporation,

New York.

The use of the method according to the invention to reduce the development of fluorine-containing gases in the methods of the prior art for the production of phosphatic fertilizer materials has the advantage that it is in the

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generally is not necessary, the Paktoren which be the reaction between the phosphate rock and acid _r agree to vary, ie, (1) the degree of purity to which the phosphate rock is ground, (2) the reaction temperature, (3) the concentration of the used special acid. Although the process of the present invention can be used in conjunction with many prior art processes, as described above, without changing the proportions in which the rock and acid are mixed, it is clear that some of the acidity is due to the added alkali metal or alkaline earth metal compound is neutralized. It will therefore be necessary to increase the amount of acid by a small amount in order to produce the same grade product. The exact amount of additional acid required can easily be determined empirically by one skilled in the art. For example, it has been found that when a sodium compound is added in a triple superphosphate process, the optimal amount of additional PpOc * i is only about one third of that required to form monosodium phosphate.

The acid concentrations and proportions of acid per phosphate rock obtained by the method of this invention are therefore generally the same as before. For example, when manufacturing of normal superphosphate by acidifying the phosphate

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steins o worked with sulfuric acid with acid concentrations in the range of about 60 to 80 ° /, preferably _f and from about 67 to 72%, the degree of acidification may be from about 0.5 to 2.5 parts of 100 $ strength sulfuric acid per part of available P ₂ 0c content in the product is sufficient. Similarly, when phosphoric acid is used to treat the phosphate rock to make triple superphosphate, an acid at a concentration of about 35 to 115 ^ H ₅ PO ₄ , preferably about 67 to 77 $ H ₅ PO ₄ , is used. The ratio of phosphoric acid to phosphate rock will be in the range from about 1.1 to 2.6 parts, preferably from about 1.7 to 2.0 parts of phosphoric acid per part of phosphate rock, for example a 32% PpO ^ rock.

Depending on the requirements of the process and specifically used and the nature of the phosphate rock, the rock is generally ground to a fineness that about 80 i "through a 100 mesh screen to about 95 ° /> through a 200 mesh screen on Tyler Base to be let through. The phosphate rock is, which in turn depends on the specific process used, mixed at room temperature with acid, which is either at room temperature or is preheated, for example to a temperature of about 65.5 ° to 121 ⁰ G, so that a reaction temperature of at least about 100 ⁰ C is present.

The alkali metal or alkaline earth metal compound, wel-

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Which is added according to this invention can be added to the mixture of acid and phosphatic material, for example the rock, in various ways. Thus, the added compound can be combined with the rock before acidification, or added to the acid before it is combined with the rock, or added directly to the mixture of acid and rock. However, it is preferred to add the alkali metal or alkaline earth metal compound to the acid some time before (but not necessarily immediately before) it is combined with the phosphate rock, as this is the most efficient distribution of the compound in the acid-rock mixture and therefore the most economical application of the compound is achieved. The alkali metal or alkaline earth metal compound can be added in any form, for example it can be added directly or first added to an amount of water or phosphoric acid which is then combined with the much larger volume of phosphoric acid used in the process. It is preferred to add the compound in an aqueous solution, for example as an aqueous solution having a concentration of about 50 ^u / o.

Although any alkali metal or alkaline earth metal compound, which provides the corresponding alkali metal or alkaline earth metal ions in the acidic medium is used can be, the alkali metal compounds are the preferred

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added compound class. From an economical point of view, sodium and potassium compounds are preferred, and including in particular the sodium compounds, the various alkali metal or alkaline earth metal compounds, which can be used according to the method according to the invention can be and comprise solids or liquids the oxides, hydroxides and the various salae more organic and inorganic acids such as the carbonates and bicarbonates, the nitrates, sulfates, acetates, and citrates similar. Specific examples of useful compounds are sodium hydroxide, sodium carbonate, sodium bicarbonate, Sodium chloride, sodium sulfate, sodium tetraborate, sodium acetate, Sodium citrate, sodium formate, sodium perborate, Sodium sulfite, potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium nitrate, lithium acetate, lithium carbonate, Lithium hydroxide, calcium carbonate, calcium hydroxide, calcium nitrate, calcium sulfate, calcium formate, magnesium carbonate, Magnesium hydroxide, barium carbonate and the like. Preferred compounds are sodium hydroxide and sodium carbonate.

It is preferred if the alkali metal or alkaline earth metal compound, which is added has an anion that only contains non-harmful materials in the Mixture of acid and phosphate-containing material forms therewith the formation of harmful "materials other than hydrofluorosilicic acid is prevented, For example, the use of sodium chloride would prevent the emission of fluorine-containing gases

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prevent, however, hydrochloric acid would be another harmful material, during the various stages of the Manufacture of phosphatic fertilizer. However, even if another become harmful Material as hydrofluorosilicic acid (and possibly Silicon tetrafluoride), the other advantages, e.g. the better handling properties, which are here already discussed, still preserved. Regarding the amount of alkali metal or alkaline earth metal compound, which to suppress fluorine-containing gases according to this Invention is used, there is no critical limitation. Although it is only assumed that cations, which is provided in the acidified mixture by adding the alkali metal or alkaline earth metal compound chemically with the fluorine (and silicon) content of the acidified mixture combine and form the corresponding silicofluoride, the amount of fluorine which is to be The beginning is present in the acidified mixture, as a basis for determining the amount of alkali metal or Alkaline earth metal compound used. It is clear that the fluorine content of the acidified mixture to be considered the! fluorine, ζ, Β present in the phosphatic material. in the phosphate rock, and that of the "wet process" phosphoric acid if used.

In general, the amount of the alkali metal or alkaline earth metal compound used is preferably between

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about 0.3 to 3.0 of the theoretical amount which can be chemically combined with the total fluorine content of the acidified mixture is required and forms the corresponding silicofluoride. Specially added amounts are about 0.1 to 1.0 moles of the alkali metal per mole of fluorine and provide about 0.05 to 0.5 moles of alkaline earth metal per mole of fluorine, preferred and of these are amounts of about 0.15 to 0.82 moles of alkali metal per mole of fluorine and about 0.075 to 0.41 moles of alkaline earth metal per mole of fluorine most preferred. However, larger or smaller amounts can be used, depending on the desired level of suppression the fluorine volatilization depends. Thus, added amounts of 0.08 moles of alkali metal per mole of fluorine and 0.04 moles of alkaline earth metal per mole of fluorine and even smaller than this can be used. Larger quantities, e.g. in the area of about 1.2 moles of alkali metal and 0.6 moles of alkaline earth metal per mole of fluorine can be used, however there is a practical limit to the amount of alkali metal or alkaline earth metal compound which is effective and is used economically to suppress the escape of fluorine-containing gases. It has been found that when the Amount of alkali metal or alkaline earth metal compound, which is added to the acidified mixture increases, the amount of fluorine decreases, which increases with further additives connects. However, the original alkali metal and alkaline earth metal content of the phosphate rock (and the phosphorus

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acid by the "wet process", if this is used) little influence on the fluorine, which will combine with the alkali metal or alkaline earth metal cations, which are added according to this invention.

The following examples are intended to illustrate the effectiveness of the method according to the invention:

Example I.

Ten 100 g samples of a finely divided Florida pebble phosphate (pebble phosphate) with a P2O5 content of 33 _f $ 8 and a Pluorgehalt of 3.89 were g each with 175 »3 g chemically pure phosphoric acid of a concentration of 75 $> I % P0 ^ (54 ft P0O5) acidified. Prior to mixing the individual samples of phosphate rock and phosphoric acid, a known amount of alkali metal compound was added to each containing a different amount of phosphoric acid than a control sample, as shown in the following table. The amounts of Na ₂ OO shown in the table are percentages by weight of Na ₂ CO *, based on the weight of the rock. The amounts of all compounds other than Na ₂ CO, are for the purpose of comparison in stoichiometric equivalents of Na ₂ GO-? given, based on the weight of the rock.

The mixtures of acid and rock were stirred for 15-20 seconds and the resulting masses were allowed to settle. The green acidified materials were then pressed separately through a 9 »525 mm masoh sieve, on pan

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Spread out of stainless steel and dried at 50 ° C for 24 hours in a laboratory drying oven with circulating air. During the analysis, the fluorine content of the individual dried samples was found as shown in the following table:

Added to acid . Fluorine im product sample
No. link percent
added Gram
found Percent to
restrained 1 - - 2.40 62 2 NaOH 3 3.45 89 3 NaOH 6th 3.54 " 91 4th NaOH 9 3.47 89 VJl Na ₂ CO ₃ 3 3.55 91 6th Na ₂ CO ₃ 6th 3.29 85 7th Na ₂ CO ₃ 9 3.50 90 8th Na ₂ B ₄ O ₇ 3 3.18 82 9 Na ₂ SO ₄ 3 2.93 75 10 K ₂ SO ₄ 3 2.86 74

Since chemically pure phosphoric acid was used for these experiments, the amount of fluorine introduced into each was Try only the 3.89 g in each bone sample. From the above Table shows that there is a significant increase in the fluorine retained in the product and therefore a corresponding reduction in fluoride volatilization revealed in all experiments where alkali metal additions were made when compared with the control sample "

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(Sample No. 1). It can thus be seen that a substantial suppression of fluorine leakage occurs when alkali metal is added in amounts ranging from 3 to 9 fo , based on the weight of the rock, which is approximately an added amount in the range of 0.27 equaled up to 0.82 moles of alkali metal per mole of fluorine,

Example II

The above results have been confirmed in tests with full-grade systems. In such a test, an aqueous Hatriumhydroxydlösung having a concentration of 50 ° was / o added to a phosphoric acid from wet-process at a level of 3.2 wt .- $ of the acid, so that an acid was obtained which 48.4 $ P ₃ O ₅ , 2.23 ^σ /> fluorine and 1.96 % Na ₂ O and had a specific gravity of 1.749. The acid was added to a 34.3 $ ^ p ^ 5 ^en " ^fc ^ ^la l ~ ed phosphate rock with a fluorine content of 3.77 ^ to produce triple superphosphate. The green triple superphosphate was analyzed to contain 45-3 % total P ₂ Q _5, 2.05 fo citratunlösliches P ₂ O _5, 1.57% Na ₂ O and 2.77 $ fluorine. analyzes of gas samples within a subsequent product conveyor belt, which resulted from the Ansäuerungsanlage to the drying facility, showed that the fluorine-containing gases in the conveyor passage were only loaded with 20% of the amount than when no sodium hydroxide had been added.

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like the materials removed from the scrapers of the acidification plant when sodium hydroxide was added and not added, the addition of sodium hydroxide results in a $ 77 reduction in fluorine-containing gases evolved in the acidification plant.

Although the invention has been described in terms of specific embodiments, it will be apparent be that obvious changes can be made without departing from the intended aim of this invention to deviate.

- patent claims -

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Claims (1)

Patent claims: 1. Method of making egg: ^; !. fixed pho <- · phatisehen fertilizer material 'jei wslohom a foinverteiltes, fluorine-containing phosphate ■: aj te in and nroi ^^ i / mixed liüche acid and at a temperature of mindöErtens about 100 ⁰ C, but unterhsVo ^ t m 28S ⁰ G aur reaction are brought to form a Superpho ^ ^ IUJ fertilizer, wobol normally fluorine halt owned Ga> enteric Ice It will !! · iUiduroh genennaeichnet that a Alkallmetali- or üirda Ib ₁ Luülj UiIiverbindurig to the G-Jaiiuch given vd.rd, which iliw οα ',. ^ ν . ;;; called alkali metal or alkaline earth installations I, .Ι ^ ιη tosagt Gemlooh supplies, and the said compound in, aucreiehortden quantity zuicgai to vdrd, that bbp. says «ao Kr \ chemisch with at least ·, .na olnera part of the? La - jr ^ eihp1ts mixture "united unc! Ir the phonpha uLöcnen" Düt-iivji » ¹ it i" ^ L a connection picture it-, vfeluhe tlac ICat Lon and FLiiur E.U '<URU t so äeß the amount da.L' he Λ-lan .ydokül £ Luorhaltigen (la-jt; 9t: is rringert. 2. Method naoi = claim 1, characterized in that at least · 3ΐΐ · 3 oüura from the group formed by FiLoaiJlioisiiuiu and sulfur oil with the bc-ina ^ er · Pt.ooc! >l; , rock is made to react and says € Alitoliiiwt, ··? ι! or Järdalkalim "t; all connection aur Gruppe am ' //,yd.*" -J ^ h .--- oxyda and salts belong " 3 »Method according to Anapruoh 2, thereby BATH ORIGINAL 009886/1676 net that the acid is phosphoric acid. 4. The method according to claim 2, characterized in that that an alkaline earth metal compound is added in a BJaLi so that about 0.05 to u.5 moles of alkaline earth metal ; per mole of fluorine are present in said mixture " 5. The method according to claim 4 »thereby ^ okernselehnet that the alkaline earth metal compound is added to a It is shown that about 0.075 msec. 0.41 moles of alkaline earth metal each MoJ fluorine are present in said chemistry, 6 «Method according to claim 2, characterized that an alkali metal compound is added in an amount is, Jeß about 0.1 to 1.0 moles of alkali metal per mole of fluorine are in said mixture, 7. The method according to claim. 6, characterized in that di <.Q eins 35 bia 115 5 "if.ο" thosphoric acid from the MaO- ν * ϊΐίϊΗ; .Γύϊχ and \ ijüB £ X ^ iu Phosphatgesteii-i in an Ans-HuerUi.ig.jvoiÄiältnis of a!; y.ii 1.1 to 2.6 ctrtsprecheriden Dimensions ■ m --- AiLr ₁ Vt c werdöHj ev - :( a ^! 3 a 'Oriple-i'uiJüji ^ hosphBtdüngemit- IeI ., ;; - M. ii.l.döb ^ U- ¹ I, - 'utü .iis bü3i ": ^ t .; TiHylo-Bupurphoaphatdii: i ^ uiu: i.t1; oil eJne ^ 3it long oinöm Lagö ^ ungsaufBohluß imter-Aivc'feii iii.id, uui dij iindg] .eiob. _< :; ai; i-; ätun8dingungen: a to achieve- 0. yö.mih / -3ii iiFiül: aiiypruoh 7, thereby gökönnzeiolinöt, doO a «uB'brJ.aiiiyerbüKiut: g au eiiiar 67 to 77 ^" IgQn, / & uö dam ίΤαβγίΗ-lead in oinem MetQ ssuggaben 009888/1876 bad original becomes that 0.15 Ms 0.82 moles of sodium per mole of total fluorine in "said acid and rock and the acid to which the sodium compound was added is mixed with the phosphate rock in a proportion corresponding to an acidification ratio of about 1.7 Ms 2.0., 9. The method according to claim 8, characterized in that that the sodium compound sodium hydroxide or ITatrium carbon is bonat. J 497
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