FR2476055A1 - PROCESS FOR THE THERMAL TREATMENT OF PHOSPHATE ROCKS - Google Patents

Abstract

THE INVENTION RELATES TO THE TREATMENT OF PHOSPHATE ROCKS. PHOSPHATE ROCK IS SUBJECT TO A THERMAL TREATMENT BETWEEN 380 AND 660C WITH A VIEW TO THE TRANSFORMATION OF ORGANIC MATTERS INTO FILTRABLE CARBON; THE ROCK THUS TREATED CAN BE TRANSFORMED TO WET PHOSPHORIC ACID OF PALE COLOR AND WITH REDUCED FOAMING. ROCKS WITH A HIGH CONTENT OF ORGANIC MATTER SOLUBLE IN ACIDS BUT A LOW TOTAL ORGANIC MATTER AND ROCKS WITH A HIGH CONTENT OF THERMOLABILE IRON SULFIDE INSOLUBLE IN ACIDS ARE APPROPRIATE FOR IMPLEMENTATION. APPLICATION: THERMAL TREATMENT OF PHOSPHATE ROCKS AND OBTAINING PHOSPHORIC ACID BY WET WET.

Description

The present invention relates to a method of treatment

  thermal, in particular heat treatment of rock

phateas or natural phosphates.

  Rocks based on calcium phosphate contain many impurities including organic compounds such as for example humic acid. Organic impurities can cause significant foaming when treating the rock with acid to obtain calcium sulphate and wet phosphoric acid and also give rise to colored downstream products by example of phosphoric acid and alkaline phosphates. It is known to remove organic materials by treatment with activated charcoal, by the use of oxidizing salts which act on phosphoric acid or its salts or by calcination of the rock. During calcination, rock is usually calcined to convert organic matter to carbon dioxide, and there remains a calcined rock that is substantially free of organic carbon and suitable for conversion to downstream products at temperatures of 750 ° C.

  or above being effective for this calcination. Characteristics

  Foaming processes can be suppressed by prolonged heating at temperatures above 650 ° C without the need for complete oxidation of the organic compounds (cf.

  Chem. Eng. Progress Vol. 58, 1962 pages 91-93).

  The applicant has found that, thanks to a heat treatment,

  rock at temperatures below those indicated above, the organic compounds can be converted at least partially and usually substantially to insoluble particulate carbon, which can be filtered with calcium sulphate during subsequent acidification to

  form phosphoric acid wet.

o o e / O. O

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  The present invention thus relates to a method for the treatment of

  phosphatic rocks. This process consists in heating the rock

  phosphated cheese containing organic compounds at a temperature between 380 and 600 ° C to convert at least a portion of the organic compounds into carbon to provide a heated rock

  comprising carbon particles. Preferential heating rock

  comprising carbon particles is reacted with a mixture of sulfuric acid and phosphoric acid to form

  a solid fraction comprising calcium sulphate, particles

  carbon and wet phosphoric acid and the acid is separated from the solid fraction. The phosphate rock is heated to a temperature sufficient to convert at least a portion of said impurities, and preferably substantially all of them into particulate carbon, but insufficient to cause the calcination of all the carbon into a carbon monoxide. of

  way the treated rock contains carbon particles.

  When the rock thus treated is reacted with the acid, a mixture is formed comprising phosphoric acid, sulfuric acid, calcium sulphate, usually in the form of

  gypsum, carbon particles and usually a weak quer.-

  rock not attacked; the mixture can be filtered by

  a moisture-free, carbon-particle-free acid with a significantly reduced hue, eg yellow rather than brown

  deep acid from untreated rocks.

  The heating of the phosphate rock by the method of the present invention

  This invention allows the reaction with the acid to proceed more satisfactorily, with less or no foam, than if untreated rock is attacked, so that the acidification is advantageously effected by almost total absence of any anti-foam agent, the reaction with the rock can also be

  be performed with a filtration speed and a speed of

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  at higher rock than if rock burned at 9500C

  is attacked. Furthermore, heating in the process of the invention

  This reduces or eliminates the need to use activated charcoal or oxidizing agents for the acid or its salts to reduce their color. The lower heating temperature represents

  also a significant economic benefit.

  The rock is heated to a temperature of 600 ° C at most, for example between 380 and 600 ° C, preferably between 450 and 600 ° C and

  more particularly between 510 and 590 ° C or 450 and 550 ° C, for example

  between 460 ° C and 540 ° C. Temperatures ranging from 380 to 500 ° C., for example from 380 to 480 ° C. and more particularly from 380 to 440 ° C.

  from 420 to 480 ° C, can be used, but the conversion rate

  The carbon content of organic materials is lower than at higher temperatures. The rock is usually heated to the indicated temperature for 0.01 to 10, for example for 0.1 to 10 hours and preferably for less than 2 hours, for example for 0.6 to 2 hours for batch processes, or for 1 minute to 1 hour, for example for 2 to 40 minutes for continuous processes, these times being in inverse function to the

temperature.

  The duration and the temperature are chosen so that, preferably, at least 30% and more particularly at least 80%,

  organic compounds are converted into carbon. Combinations

  Particularly useful are: 40 minutes to 2 hours at 450-550 ° C for Florida or Zin rock for batch processes or 15 minutes to 2 hours, eg 1 hour, at 450-5500C for continuous processes , while for the rock of Morocco (for example the rock of Khouribga or

  the white rock of Youssoufia) durations from 30 minutes to 2 hours

  It is preferred at 380-440 ° C for batch processes or 15 minutes to 2 hours, for example 15 minutes to 1 hour at 380-440 ° C for continuous processes. The temperature range of 380 ° C to 440 ° C is also advantageous for the Syrian rocks of Senegal, Algeria, Jordan, while the range of 560 ° C

  at 590'C is useful for the black rock of Youssoufia.

  Preferably, when the rock is heated in the range

  from 460 to 540 C it is not of Egyptian origin, if the treatment

  temperature is between 490 and 5100C, nor of Russian origin, if the heat treatment is between 490 C and 540 C and it is not Florida if it is heated between 490 and 51000 unless heat treatment is continuous rather than discontinuous. When the rock is heated between 510 and 5900C,

  preferably not from Utah or Morocco if the heat treatment is

  between 540 and 5600C, nor of Russian origin if the treatment

  temperature is between 510 and 540 ° C and when the treatment

  thermal is carried out between 440 and 4600C the rock is preferably

  not from Utah or Morocco. In the case of original rocks

  Egyptian, Russian, Florida, Utah or Morocco the temperatures

  above can be used in continuous processes.

  bare. A mixture of these rocks can be used.

  Although conventional calcination at 6500C or above furnace

  a significant amount of hydrogen fluoride in the ef-

  gaseous fluent from heating, heating to a temperature of

  The lower temperature according to the invention gives much less fluoride.

  re, often almost no fluoride in the effluent, making

  the purification of this effluent easier.

  The heat treatment can be carried out under conditions

  practically anaerobic in the absence of free oxygen (or another agent capable of oxidizing organic impurities); this is how the rock can be heated from the outside in

  the absence of air, for example in an oven away from the air. This-

  during, the rock advantageously heated in the presence of a gas comprising molecular oxygen, for example air, or combustion gas comprising air and in the absence of compounds

  added and in the absence of oxidants (except for oxygen

  ne) capable of oxidizing organic impurities; there is no pre-

  No chlorine and / or hydrochloric acid added to the gas. The rock can be heated by an oxidizing flame in an oven to the required temperature. The heating can take place with a defect of oxygen compared to the quantity necessary for the transformation of the organic impurities in carbon, but one

  preferably uses at least the required amount and in particular

to bind an excess.

  Conditions are usually sufficient to give

  a heated rock comprising carbon particles and practically

  no organic compounds that are soluble in acids (such as

  as defined below) and often hardly any other

organic ses.

  The heat treatment is preferably carried out in

  naked so that the rock passes continuously in at least one zone heated to 380-600C so as to transform at least a portion

  organic carbon compounds and a heated rock

  carbon particles is withdrawn and usually

  froidie. The heat treatment is generally carried out at a temperature between 380 and 600 ° C without the temperature

  subsequently exceeds 600 ° C; the temperature of the rock is

  reduced suite. Preferably, a rotary kiln is used with

  If the hot combustion products of the flame or rock can be mixed with the fuel and the fuel is burned and the rock heated at the same time the passage of rock and fuel in the calciner. Alternatively, a fluidized bed of rock and hot gas may be used or the layered rock may continuously pass under the flame or through an externally heated zone. Annular or tunnel furnaces

  can also be used. Although heat treatment can

  The rock preferably has a particle size of less than 5 mm and is preferably milled to a particle size of 0.01 to 1 mm, for example 50%. at least between 0.01 and 5 mm and preferably

  with less than 30% less than 0.1 mm.

  The rock may contain 0.05 to 6%, for example 0.05 to 1% or 0.5 to 6.0% or 1.0 to 6% organic matter (expressed as organic carbon) and than classical rock impurities. The rock can thus contain (by weight) 15 to 45% of P 2 O 5, for example 25 to 40% of P 2 O 5F 25 to 35% or 30 to 40% and in particular 30 to 35% of P 2 O 5, 25 to 55%, for example 45 to 55% or 50 to 55% of Ca expressed in CaO, 0.01 to 8%, for example 0.05 to 0.5%

  or 0.5 to 5% Fe2O3t with total iron and aluminum content

  eg less than 10%, for example less than 4% by weight (expressed as Fe 2 O 3 and Al 2 O 3) and 1.0 to 7%, for example 1 to 3.5% or 3.5 to 7% carbonate (expressed as CO2). The invention is particularly suitable for the treatment of phosphatic rocks of

  apatite type, for example those which, after digestion with the

  27% hydrochloric acid, form brown liquids; examples of such rocks are those of Zin in Israel and Florida. We

  can also treat other rocks, for example

  from the Western States of the United States such as Idho or elsewhere, such as those of North Carolina,

  Tennesee, Tunisia, Jordan, Morocco (eg Yous-

  soufia) from Algeria, Senegal, Kola, Nauru or Oceania. The phosphate rock preferably contains 0.05 to 0.4% organic material or a weight ratio of organic materials to P2 0 of 0.001 to 0.1: 1; rocks with a low content of materials

O O. /. O

  examples are those of Zin (Israel), Khouribga (Morocco), El Massa (Jordan), Ageria, Tunisia, Senegal

Oron (Israel).

  The process is particularly suitable for the treatment of rocks containing soluble organic matter substances in the

  acids (as defined below). The expression "materials

  acid soluble gums as used in the present invention.

  This description refers to the organic compounds found in

  phosphatic rocks which are of such nature and in such quantity that after digestion of the rock with a mixture of 56% sulfuric acid and 20% thermal phosphoric acid (said mixture

  containing enough sulfuric acid to transform the oxy-

  of calcium from the rock to calcium sulphate) they form a suspension in a liquid containing 25 to 30% of P2 05 containing

  at least 600 ppm (eg 600 to 60,000 ppm) of organic materials

  dissolved solids (expressed as total carbon), namely a weight ratio of dissolved organic matter (expressed as total carbon) to P2 0 in the liquid of at least 0.002: 1, for example

  0.002 to 0.2: 1; as a variant, the content of the liquid made of

  In the case of dissolved gaseous hydrocarbons, the amount of oxidizable carbon is at least 100 ppm, for example from 100 to 10,000 ppm, ie a weight ratio of organic materials to P2 0 of 0.0003: 1, for example from 0.0003 to 0.03: 1. It is these rocks that provide acids containing the highest amounts of dissolved organic matter,

  which can be more usefully enhanced by heat treatment.

  of the invention so as to provide rocks treated with

  from which can be extracted an acid containing

  lower organic matter (eg 500 ppm or

  less total carbon or 50 ppm or less of oxidizable carbon).

  Among the rocks that can be treated by the process

  of the present invention include those where the rocks themselves

  same have a low organic matter content, eg 0.05 to 0.4% (total carbon), but these organic

  are soluble in acids as specified above.

  Such rocks come from, for example, Zin in Israel, Alge-

  Tunisia, Jordan and Senegal. In another aspect, the present invention relates to a method for the heat treatment of

  phosphate rock, characterized in that a phosphorus rock is

  phatea, comprising in total 0.05 to 0.4% of organic compounds (ex.

  rewarded with carbon) and organic matter soluble in

  of, is subjected to a heat treatment between 380 and 600'C for the transformation of at least a part of the organic compounds

  carbon to form a heated rock with particles

  carbon. The rock preferably comprises 30 to 40% of P2 O5

  and 45 to 55% of Ca expressed as CaO.

  The plaintiff further found that with the phosphoric rocks

  Heat treated at 650 ° C provides a treated rock which, after acidification with a mineral acid, gives hydrogen sulfide in different amounts depending on the rock and that,

  when the rock is subjected to heat treatment by the

  According to the invention, at a lower temperature, for example 380 to 6000 ° C., the amount of foul-smelling and toxic hydrogen sulphide produced during the acidification can be reduced together with the iron content of the acid. It is estimated that this

  high temperature effect is due to temperature transformation.

  high levels of iron sulphide insoluble in the pre-

  in the rock is an acid-soluble iron sulphide which, at the time of acidification, forms hydrogen sulphide and dissolved iron. The low temperature can also reduce the arsenic content of the product acid compared to that obtained at

  from calcined rocks at high temperatures.

  Therefore, a particular embodiment of the pre-

  This invention consists of a process for the preparation of

  phosphoric acid in which phosphate rock, containing impure-

  organic and acid-insoluble thermolabile iron sulphide is heated to between 380 and 600 ° C to convert at least

  a part of said organic impurities into particles of car-

  but at a temperature insufficient to cause substantially all of said acid-insoluble sulphide to be converted into acid-soluble iron sulphide, the heat treatment process providing a treated rock containing

  carbon particles and iron sulphide insoluble in

  of. Preferably, the rock thus treated is then set to

  stir with the mixture of sulfuric and phosphoric acids to form a reaction mixture comprising phosphoric acid, sulfuric acid, calcium sulfate, carbon particles and acid-insoluble thermolabile iron sulfide; we separate

  then a solid fraction comprising said particles of car-

  acid-insoluble iron sulphide and sulphate of

  calcium, usually in the form of gypsum, phosphoric acid

  than wet way. The terms "iron sulphide insoluble in

  acids "and" soluble in acids "apply to those

  iron which is insoluble or soluble in a phosphoric acid

  wet process containing 28% P2O0 and 0.5% SO3. The

  term "thermolabile" iron sulphide in the present description

  means iron sulphide in rock, which can be converted by heating into an acid-soluble product from a

  product insoluble in acids. The heat treatment is

  between 380.degree. C. and 600.degree. C., for example 380.degree./480.degree. C., in particular 400.degree.50.degree. C. or 450.degree.-550.degree. C., and usually at a temperature below the phase transition temperature in this rock for the transformation. iron sulphide insoluble in a sulphide

  of iron soluble in acids. Other heating conditions

  are generally described above and the process is

  preferably carried out continuously.

  The process for avoiding the production of hydrogen sulphide can be applied to any phosphate rock, such as those described above but in particular to those containing heat-labile and acid-insoluble iron sulphide, for example in an amount of at least 100 ppm (preferably at least 500 ppm) of sulfide (expressed as weight of S), for example at 20,000, 500 to 10,000, such as 2,000 to 5,000 ppm, or at least 200 ppm ppm of metal sulphide (expressed by weight of FeS, for example 200 to 40,000, preferably 1,000 to 10,000 ppm.) The heat-labile and acid-insoluble sulphide content of the unheated rock is obtained from the maximum soluble sulphide content. in hydrochloric acid found in heated rocks

  at any temperature between 100 and 1.0000 ° C.

  examples are those of Zin, Youssoufia, Senegal,

  Iceland, Christmas Island and in particular Florida, the weather

  preferred temperature for the heat treatment being 450 to 5500C for the latter; rocks of Tennessee, North Carolina, Idaho and other western states of the United States may be

treated in the same way.

  According to another aspect, the present invention relates to a rock

  heated phosphates comprising carbon particles and sulfur

  The acid-insoluble heat-labile iron of which at least 1%, for example at least 80%, preferably 80 to 98% or at least 90%, is insoluble in acids and the remainder is optionally soluble in acids. The rock preferably contains at least 500 ppm, for example 500 to 5,000 ppm, of said iron sulfide

  thermolabile insoluble in acids (expressed in S).

  The heat-treated rock comprising carbon particles (whether or not containing iron sulfides) may be reacted with at least one of the sulfuric or phosphoric acids to form calcium phosphate useful as a fertilizer. The reaction with phosphoric acid gives a triple superphosphate fertilizer, while the reaction with sulfuric acid gives a superphosphate fertilizer comprising diacid calcium phosphate and calcium sulphate. Preferably, the amount of acid and at least, for example, 80 to 120% of the amount needed to react with the calcium in the rock to form calcium phosphate

  diacid when the acid is phosphoric acid or

  necessary to form the calcium phosphate mixture di-

  calcium sulphate (and practically no phospho-

  free) when the acid is sulfuric acid. Preferably

  the rock has been heated to a temperature

  460 and 540C and is not from Morocco or Utah, unless the

  temperature has been maintained at a temperature of 380-440 ° C, or between 560 and 600 ° C, or unless the rock is reacted with sulfuric acid or a mixture of that acid with phosphoric acid, or unless the rock has been heated to

during a continuous operation.

  According to one embodiment, the rock is reacted with

  taking carbon particles with phosphoric acid or

  sulfuric acid but not with a mixture of these two acids.

  Calcium phosphate fertilizer may be mixed with nitrate

  or ammonium phosphate solution or in solid form and optionally with potassium chloride to form

  compound fertilizers after mixing and granulation.

  The thermally treated rock can also be reacted with a mineral acid such as hydrochloric acid, nitric acid or sulfuric acids to form a mixture of their salts.

  calcium from phosphoric acid and carbon particles and separated

  the solid fraction comprising the carbon particles of said mixture. Preferably, the rock is heated to between 380 ° and 59 ° C., especially when the acid is only hydrochloric acid and the rock is preferably not from Florida or Morocco unless the heat treatment has taken place between 380 ° and 60 ° C. 590C or unless heat treatment is part of a process

  continuously. Preferably the rock is reacted with a quanti-

  acid equivalent to at least 90% of the calcium content of the rock so as to convert the phosphate contents of the rock into phosphoric acid. Although hydrochloric acid can

  be used as a driving acid, an acid is preferably used.

  such as nitric acid or sulfuric acid, because then the separated solid fraction also contains nitrate or calcium sulphate respectively, which then reduces the calcium content of the

  liquid left after separation.

  During the transformation of thermally treated rock into wet acid, whether the rock contains a significant amount of iron sulphide or not, the rock is treated with sulfuric acid and acid. phosphoric acid to produce a reaction mixture containing a liquid fraction and a solid fraction, in which solid fraction the proportion

  is calcium sulphate and the proportion of

  minor by carbon particles (and possibly iron sulphide) and usually some untouched rock. The

  the amount of sulfuric acid is usually such that it trans-

  at least 90%, for example at least 95%, of the phosphate content of the rock into wet phosphoric acid or is equivalent to at least 90% of the calcium oxide content of the rock, preferably 95 to 105%. The reaction of the treated rock with the mixture of phosphoric and sulfuric acids can be carried out at low temperature and at a low concentration of sulfuric acid

  to form gypsum, or high temperatures, for example

  above 90 ° C and with a high concentration of sulfuric acid to form calcium sulphate hemihydrate or anhydrite. The rock is suitably mixed with sulfuric acid,

  weak phosphoric acid for recycling and a suspension of

  cycled calcium sulfate in wet phosphoric acid to form the calcium sulfate slurry, a portion of which is recycled and the remainder is separated, for example by filtration,

  and the calcium sulfate filter cake (with particles of

  the carbon and optionally iron sulphide) is washed with water to give a weak phosphoric acid filtrate, which is recycled to the rock attack stage. Wet way acid, crude

  obtained after treatment with a mineral acid and separation of

  solid materials, can be used as such, in particular when the calcium sulphate has been separated, or can subsequently be treated, often after concentration up to, for example, 40 to 60% P2O5 in the case of an attack with a sulfuric acid mixture /

Phosphoric acid.

  Raw wet phosphoric acid obtained after treatment

  rock treated thermally with a mineral acid and separated

  The solid fraction, with or without concentration, can be treated with an organic solvent immiscible with water to form an organic phase and an aqueous phase with recovered acid.

  at least one of these phases. The heat treatment process

  according to the invention decreases the production of emulsions at this stage.

  and increases the rate of phase separation from that obtained when the heat treatment does not take place. Preferably, unless the rock has been continuously treated as described above, the rock has been heated to 380-590 ° C when the acid is only hydrochloric acid and said organic phase contains phosphoric acid dissolved. The solvent may be a solvent in which the phosphoric acid is practically not soluble or which

  is unable to extract phosphoric acid from phosphoric acid

  aqueous phoric of a given concentration so that the sol-

  It extracts the impurities leaving most of the phosphoric acid in the aqueous phase. The impurities may be simple contaminants to be removed, for example iron or may be

  in themselves valuable compounds, such as uranium. Examples

  Examples of solvents for removing iron from the usually insoluble acid from dilute phosphoric acid are long chain amines, alcohols, ethers, esters and ketones. Examples of solvents for removing uranium from the acid, usually without concentration, are the trialkyl-phosphorus oxides.

  phine, for example trioctylphosphine oxide, dialkylphos-

  phates, for example di (2-ethylhexyl) phosphate or in particular

  mixtures of these compounds or, alternatively, monoalkyl-pyro-

  phosphates, such as monoactyl pyrophosphate, and / or dialkyl

  pyrophosphates or alternatively mono (alkyl-phenyl) phosphates and / or di (alkyl-phenyl) phosphates, in particular mixtures of these compounds, such as salts of mono- and di (octyl-phenyl) phosphoric acids. In each case the alkyl group contains 6 to 12

carbon atoms.

  When using phosphine oxide and / or a diisaster with

  extraction agent, it is necessary to oxidise the uranium

  than at valence 6 and accordingly the iron present in the acid is

  inevitably also oxidized. The implementation of the treatment process

  The heat treatment according to the invention often reduces the iron content of the acid relative to that obtained from calcined rock.

  at high temperature and therefore less oxygen is needed.

  to oxidize uranium. A product containing uranium can be recovered from the organic phase, for example by re-extraction

  in aqueous acid and possible conversion to uranium oxide.

  The water-immiscible organic solvent can be a solvent

  which preferentially extracts phosphoric acid, leaving it

  impurities in the aqueous raffinate phase, which is ex-

  treats the organic phase containing the purified phosphoric acid, and the phosphoric acid is recovered from the organic phase in the form of phosphoric acid or / its salts, for example by contact

  with water or an aqueous phase and optionally heating.

  Examples of suitable solvents are alcohols, ethers, organic esters and ketones, of which those having 4 to 9 carbon atoms, for example butanol, are preferred.

  amyl alcohols, isopropyl ether and methyl isobutyl-

  ketone. Other esters, such as trialkyl phosphates, for example tributyl phosphate, can also be used. This solvent extraction process is highly desirable

  when the mineral acid attack is hydrochloric acid or the

  nitric acid, because it separates the phosphoric acid from the calcium salts of the crude reaction mixture. The phosphates contained in the extract can be obtained by evaporation or preferably by contact of the extract with water and / or a base. High carbon solvents are usually used with

  acids after concentration up to for example 50 to 60% in P2 05.

  The wet-path acid obtained after separation from the fraction

  solid composition, comprising carbon particles, and in particular

  bind when it comprises nitrate or calcium sulfate, can also be treated, with or without subsequent concentration up to for example 40 to 60% P2 O5 with at least one nitrogen compound,

* including ammonia, to form at least one ammonium phosphate

  monium for example a mono- and / or di-ammonium phosphate which is suitable as fertilizer. Often the ammonia is mixed with ammonium nitrate or nitric acid is added first or was the acid of attack, and the fact of using the heat-treated rock according to the invention makes it possible to use less nitrate than if one uses untreated rock, because such untreated rock and consequently the acid that comes from it

  contain organic compounds that react with nitrate

  you. The wet-path acid obtained after separation of the fraction

  solid contains carbon particles and, in particular,

  that this fraction also includes calcium sulphate, may also

  if treated with alkali to form at least one phosphate

  which is separated from all solids, such as hydroxides and phospha-

  heavy metals also formed. The alkali can be a hydroxy

  of, sodium or potassium carbonate or bicarbonate. The reaction of the base and the acid can be carried out up to a metal / P atomic ratio of 1: 1; 2: 1 or 3: 1 or preferably 1.67: 1, the latter being suitable for a subsequent heat treatment to form alkali metal tripolyphosphates. The process

  heat treatment of the rock reduces and can eliminate

  the amount of oxidant needed to discolor the liquor of

  acid or phosphate and consequently tripolyphosphate.

  In particular, when the etching acid is chloroacid

  but also in the case of nitric acid and

  sulfuric; the wet-path acid after separation of the fraction

  can be treated sequentially with a portion or

  more than one, for example 2 to 4 portions of an alkali metal base

  earthquake, for example calcium hydroxide or calcium carbonate or

  magnesium, to precipitate a number of alkali metal fractions

  lino-terrestrial (eg calcium) acid phosphate, suitable as livestock feed, which can be separated from the mother liquor which contains calcium chloride or calcium nitrate

  or water depending on the attack acid.

  The invention will now be illustrated by the following examples:

non-restrictive

  Examples 1 to 3 and Comparative Examples A to C

  A phosphate rock from Zin (Israel) had the following composition

  te: 32.0% of P2 05; 6.0% CO2; 2.0% SO3; 1.5% SiO2 4.0% F; 51% Ca (as CaO); 0.2% Mg; 0.3% Al (as Al 2 O 3); 0.2% Fe (as Fe 2 O 3) 0.9% Na (as Na 2 O); 0.2% organic matter

oxidizable (expressed in C).

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  The particle size distribution was 6.5% above 0.5 mm; 27.3% between 0.25 and 0.5 mm; 38.9% between 0.15 and 0.25

mm and 27.3% below 0.15 mm.

  A layer of the above rock was heated in an oven for one hour in the presence of air at the temperature indicated below. The treated rock was examined after cooling. The

  rocks treated at 400-700 C were dark and showed the pre-

the presence of carbon particles.

  In order to evaluate the effect of heating for the removal of

  of the organic material from the rock, the latter (heat treated or otherwise) (100 g) was gradually added to a mixture of concentrated hydrochloric acid (35%, 205 g) and water (75 g ). The temperature of the mixture was 40-45 C and the

  The mixture was then heated for one hour to the boiling point.

  The degree of foaming obtained during the reaction of rock and acid was noted. The reaction mixture was filtered while hot to remove the carbon particles from the rock

  unreacted calcium salts and then cooled to room temperature.

  ambient temperature and refiltered to give a crude phosphoric acid. The color of the crude acid was noted and the results obtained are shown in Table I.

Table 1.

  Example: Temp. of: Color of: Color of acid: Degree of: Heating: Rock:: Foaming

 C ::

  A :::: (comparative): None: sandy: deep red-brown: important B :::: (comparative): 200: "" "" "1: 400: pale black: intense yellow: 2: 450: black medium: average yellow: 3: 500: black: pale green: C :::: (comparative): 700: gray: "": weak

D ::::

  (comparative): 900: green: "": "Examples 4 to 8 and comparative example D.

  In the same way as in Examples 1 to 3, phosphoric rock

  Zin phatea (Israel) having the same composition and

  The above measurement has been heated at various temperatures and for varying periods of time. The treated rock was reacted

  with hydrochloric acid as above and, in the course of

  separate processes, with a mixture of sulfuric / phosphoric acids

  than; the color of the liquid was noted and the

  organic matter and P2 & 5 of the liquid. Sulphuric acid

  phosphoric acid was a mixture of 200 g of 20% phosphoric acid P2 O5 and sufficient 56% sulfuric acid to combine with 98% of the calcium content of the rock

  used, the quantity being such that the rock contained

  was born 40 g of P2 0 &. The amount of rock specified was mixed with 200 g of phosphoric acid at 600C with stirring. After stopping the formation of foam, sulfuric acid and

  The mixture was stirred for 2 hours at 70 ° C. to give a suspension.

  gypsum in phosphoric acid. The suspension was filtered hot and the filter cake was washed three times

  with 50 cc of cold tap water. All the filtrates were

  by giving the acid product that has been analyzed for its content

  in P2 05 & total carbon and oxidizable carbon. The rock has

  It has been analyzed for its F content before and after heating.

  The results were as follows. (See Table 2). The Zin rock before heat treatment contained 250 ppm (expressed in S)

  of acid-insoluble iron sulphide.

  Examples 9 to 18. Comparative Examples E to J.

  As in Examples 4 to 8, the same techniques were adopted

  of phosphate rock heating and reaction of rock

  with hydrochloric acid or mixtures of sulfuric acid

  than / phosphoric but with rocks other than those of Zin. -

  The details of the rocks and the results obtained are shown in Tables 3 to 5 below. Unless otherwise indicated, the heat treatment was 1 hour in each case. When digesting the unheated Morocco rock with the H2504 / H3P04 mixture, the liquid After filtration) contained 27.8% of P2 051 100

  at 200 ppm total carbon and 15 to 20 ppm oxidizable carbon.

Examples 17-19.

  Zin rock, as defined in Example 4, was subjected to continuous heat treatment in an inclined rotating calciner, in which the rock slowly moved downward against a blown air / gas stream. The residence time was 20 to 30 minutes. Inlet gas temperatures, solids at the exit point of the calciner and off-gases

  have been measured. The heat-treated rock was collected

  and treated with the sulfuric / phosphoric acid mixture as in Example 4; insoluble materials (including gypsum and carbon particles) were filtered and the color of the acid product was noted. The results were as follows: 0 ° C Solids at: Gas: Effluent Product color Example output: inlet: gaseous acid 17 430 800 - yellow orange 18 510: 880 210 very pale green 19: 520 890: 200 very pale green I ..

TABLE 2.

  The filtered liquid from ple 8 was analyzed for the following:% carbon ppm t ppm carbon oxyc

  acidifications H3PO4 / H2SO4 in comparative example E and in the example

  its content of P2 051 in total carbon and in oxidizable carbon. The results P2 05 - example E: 27.9% example 8: 29.9% total - example E: 1280

example 8: 370

table - example E: 650

example 8: nothing.

  : Heat treatment on :: Acidification with HCl: Acidification with H2SO4 / H3P04 rock:% F Example: in: Color: Degree of: Color of product acid: Temp, C: Duration (min: rock: l 'acid: foaming: :::: product ::

:: ::::

  E: Not calcined: -: 3,8: red-brown: important: reddish brown 4,400: 15 intense :: light reddish brown: 400: 60: 3,8: yellow: light: yellow 6: 500: 15 :: - :: pale yellow

7: ": 30: 3,9: green-yellow: weak: -

  8: ": 60: 3,8: pale green: weak: very pale green

: ..:.

TABLE 3.

Analysis of phosphate rocks.

Source of the rock.

  P205 CaO Na2O MgO to 203 Fe2O3 S03 SiO2 F CI

*:..Morocco.:. Jordan: Florida.

(Khouigba):

31.5

51.2

: 0.7

0.8

0.40

: 0.21

2.4

2.1

6.4

: 4.0

: 0.03

  % of organic materials: in the form of C 0.18

33.9

52.8

: 0.57

: 0.29

: 0.28

: 0.09

2.37

1.37

4.46

: 3.88

: 0.06

31.3

45.1

0.6

0.75

1.8

2.4

: 5.9

: 3,3

3.6

3.8

: 0.005

0.30 1.56.

: 0.30: 1.56

  % weight loss after: heating to 105 C 1,1

1.2: 0.8

  Particle size analysis,% by weight Granulometry: Morocco: Jordan: Florida

Greater than 1.2 mm 63: - -

  0.5 mm - 1.2 mm: 10: 38: 35 0.25 - 0.5 mm: 7: 24: 39 0.15 - 0.25 mm: 15: 27: 23 Less than 0.15 mm: 5..:. 1.1 .: 3%%%%%%%%% _I

TABLE 4.

  Acidification with hydrochloric acid of a given rock Heat treatment temp. C Untreated: Example: Morocco :: Color of :: acid: Morocco: Degree of: foaming E: 5a intense: important 9: intense yellow: medium: yellow: moderate

F: yellow: negligible

  :: ble: Example: Jordan: :: Color of: :: acid: G: pale yellow:

: 1: -:

  : 14: pale yellow: :: with a: :: green shade: I Identical foaming degrees were obtained when the rocks were treated with the mixture

  phosphoric acid / sulfuric acid as in Example 4.

  Ltn Ln o do cN cN Jordan Low light foaming degree

TABLE 5.

  Results on Florida rocks Heat treatment Acidification by H "ii Acidification by H2S04 / H3PO4 Tempo C Time Color Degree of Color Degree of: * * .:: acid foaming acid: foaming ::.: H: ' :: i * H: uncalcined: yew-red-brown-important * - * - to. * igeâtre 13 400 1 H: - light yellow-brown: weak 14. 500 1 H: medium orange-brown: very brown-yellow 5.5 * 0 *. * Weak blade

15. 0o 2 H: pale yellow i weak - -

  16 * 600 * 1 H: yellow green * weak -

  J 900 i 1 H: orange-yellow none green very pale i weak to .. * almost colorless: ::: *

Example

  Examples 20 to 22 and Comparative Examples K to N.

  Florida rock having the composition indicated below

  The above was heated for 1 hour at various temperatures and the treated rock was then reacted with the sulfuric / phosphoric acid mixture as in Example 4. A solid comprising calcium sulfate, carbon particles, and Iron sulfide was separated from the reaction mixture leaving an acidic product. The treated rock was treated with 14% by weight hydrochloric acid and analyzed for soluble iron content and

sulfide.

  The results were as follows.

  Example Temperature: Analysis of the rock Sulfide, ppm% of soluble iron example without comparison: treatment 70: 0.57 K: thermal

20 400 110 0.73

21,500 220 0.76

22,600,980 0.94

example

comparative 650 2180 1.12

The

example

comparative 750 3360 1.35 M

example

  Comparative 900 110 1.36 N Example 23 and Comparative Example P The acids of Example 8 (obtained by heat treatment of the rock at 5000C for 1 hour) and Comparative Example E (from a non-calcined rock) were separately admixed at 350 ° C, in a weight ratio of 3: 2, with separate solutions of 0.5 M di (2-ethyl-hexyl) phosphoric acid and 0.15 M trioctylphosphine oxide in petroleum ether having a boiling point between 100 and 120 ° C and the phases were allowed to separate. The phases immediately separated with the acid of Example 8 into an aqueous acid phase and an organic phase, which was separated and its uranium content was recovered by treatment with aqueous phosphoric acid containing ions

Ferrous (Example 23).

  With the acid of Comparative Example E, mixing the acid with the petroleum ether solutions gave an emulsion which became clear after 5 minutes giving aqueous phases

  and organic (Comparative Example P).

  Examples 24 to 26 A rock corresponding to the analyzes of Example 38 below was heat-treated for 1 hour at 500 ° C. according to the procedure described in Example 1. Wet phosphoric acids were prepared from this method. rock and also from the untreated heat rock, by reaction with a mixture of sulfuric and phosphoric acids (as described in Example 4) and separation of a solid fraction comprising

  gypsum, carbon particles and unattacked rock.

  Wet acids were also prepared from rocks corresponding to the analyzes reported in Example 1 and Example 27 below. Prepared wet acids

  Examples 42 to 44 below, from heat-treated rocks

  mically, were also used. Each acid has been concentrated

  and boiled by bubbling with air to reduce the Fe II content. Each of the 6 acids, which contained an amount of P2 O5 of the order of 24 to 29%, was mixed with stirring at a temperature of

  temperature of 35WC in a 1: 1 volume ratio, with a solu-

  of 0.5M di- (2-ethylhexyl) phosphoric acid and 0.15M trioctylphosphine oxide in petroleum ether (boiling point).

  100-120 ° C). After shaking for 5 minutes, the

  They were left at rest. In 40 seconds, each mixture

  Wet acids obtained from thermally treated rocks separated into an organic phase comprising uranium and an aqueous acidic phase. For each of the mixtures

  obtained from acids from untreated rock

  only a large amount of interfacial solid debris and an interfacial emulsion which required 10 to 30 minutes before breaking up into an organic phase comprising uranium and an aqueous acid phase. In each case, the two phases

  were separated and the uranium collected from the organic phase

  by extraction with aqueous phosphoric acid contained

ferrous iron.

  Examples 27 to 38 and Comparative Examples Q to U In these examples, the following rocks were used, the analyzes of which are reported hereinafter. Florida's Rock II came from a different mine than the Florida rock used

in Examples 13 to 16.

  Florida Rock II Youssoufia Black Rock (150 C 2 hrs.) Youssoufia Senegal White Rock In each of the examples below, the rock was heated as follows. The rock in the form of a layer in a silica tray was heated in a muffle furnace with aeration to the atmosphere, maintained at a fixed temperature for 1 hour. The treated rock was then reacted with the mixture of sulfuric and phosphoric acids of Example 4 and separately with 14% (w / w) hydrochloric acid as described in the examples.

  at 22 and also with 70% phosphoric acid with sepa-

  ration of insoluble solids comprising carbon particles.

% P205 30.9 29.9 31.0 35.8

% CaO 46.0 49.8 51.0 50.1

% 503 1.4 2.0 1.2 0.33

% CO2 4.3 6.7 6.1 1.7

% Sio2 3.4 4.1

% F 3.7 3.9 4.1 3.9

  % C1 0.001 0.024 ppm <4100% Na2O 0.7 0.63 0.85 0.18% MgO 0.7 0.61 0.29 500 ppm

% A1203 0.9 0.32 0.17 0.53

% K20 0.2 0.028 40.1

  % Fe203 * 1,1 0,15 0,13 1,1 organic matter Carbon% C 0,5 1,3 0,15 1,08 Roche II of Florida Example Temperature OC Sulfide

unstable

  in acids ppm Iron soluble in acids% Fe color of acid after treatment of rock by HCI Q untreated 8 0.67 dark brown 27 500 230 0.95 lemon green 28 600 1030 1.10 lemon green R 750 3280 1.31 lemon green Youssoufia S black stone untreated - - dark brown 29 400 260 0.11 lemon green 500 220 0.11 lemon green 31 600 120 0.11 lime green 32 580 - - lemon green Youssoufia white rock T untreated - 0.11 green blue 33 400 160 0.12 lime green 34 450 - - lemon green 500 220 0.11 lime green 36 550 215 - lime green 37 600 220 0.12 lemon green Untreated Senegal stone U - - brown 38 500 - - lime green Examples 39 to 41

  In these examples, the Florida rock used in the examples

  Examples 13 to 16 were used in Example 39, whereas for the example

  Examples 40 and 40 have been used in Examples II and II, and for Example 41, Morocco rock in Examples 9 and 10. For Example 39, the Florida rock of Examples 13 to 16 was treated. thermally in an oven for 1 hour at a temperature of 550 ° C giving a gray rock containing

  carbon particles. The rock was then treated by the

  sulfuric acid and phosphoric acid mixture of Example 4 and a solid fraction comprising gypsum and carbon particles / was separated

  leaving a wet-path acid that had a pale green color

  the, compared to the dark brown color corresponding to the rock

untreated heat.

  For Example 40, Florida Rock II of Examples 27 and 28 was heat treated continuously, according to the method described in Examples 17 and 19, with a solid temperature at

  output of 5000C and the inlet and outlet gas temperatures

  790 ° C and 180 ° C respectively, with an average retention time of 20 to 30 minutes. The heated rock was treated with the mixture of sulfuric and phosphoric acids of Example 4 and

  insoluble materials including gypsum and

  have been separated from the reaction mixture leaving a pale green phosphoric acid, relative to the

  dark brown color corresponding to untreated thermal rock

is lying.

  For example 41, Morocco rock was heat-treated continuously according to the process described in Examples 17 to 19, with a solid exit temperature of 390 ° C. and the inlet and outlet temperatures of the gases of 760 ° C and 130 ° C respectively, with an average retention time of 20 to 30 minutes. The heat-treated rock comprising carbon particles was treated with the mixture of sulfuric and phosphoric acids of Example 4 and the wet acid was separated from the insoluble materials. The acid had a medium yellow color compared to the dark yellow color of the acid from untreated heat rock.

Example 42

  The phosphate rock, having the composition indicated in Example 1, was heat treated continuously according to the method described in Example 19 and the heat-treated rock was

  continuously transformed with a mixture of sulfuric and phosphoric acids

  phoric in the presence of a gypsum slurry, into a phosphoric acid

  phoric wetland with separation of a solid fraction

  gypsum, carbon particles and non-ferrous rock

  attacked. The reaction was conducted in a stirred reactor.

  in one operation by a conventional method and using

  a quantity of sulfuric acid equivalent to 102% of the

  neur in calcium from the rock. The phosphoric acid produced contained

  from 28 to 30% P 25 and no trace of oxidizable carbon. The Atta

  that in the tank did not require any addition of antifoam agent; By comparison, it will be indicated that the addition of 0.6% of acid

  oleic (relative to the weight of P205 in the rock) was necessary.

  in the case of untreated rock. The speed

  Filtration was also much faster than in the case

  of untreated rock.

Examples 43 and 44

  In the same way as in Example 42, Rock II of Flo

  wrinkle heat treated at 500 ° C continuously according to Example 40 and the rock of Morocco (Khouribga) thermally treated continuously according to Example 41 were continuously converted to a wet track acid. The phosphoric acids produced contained

  28 to 30% P205 and no trace of oxidizable carbon. No ad-

  Antifoam agent was not necessary in the

  treatment, contrary to the addition of 1.0% or 0.6% respectively

  of oleic acid (relative to the weight of P205 in

  che) in the case of untreated rock. The speed

  its filtration of gypsum suspension was also

  faster than in the case of untreated rock.

Example 45

  The wet phosphoric acid obtained in Example 42 was purified by solvent extraction. It was then concentrated to 54.7% P 2 O 5, 1.51% SO 3, 0.32% Fe, 0.24 Mg, and 0.07% Al, with less than 50 ppm. oxidizable carbon. This acid was purified in a two-stage countercurrent extraction system with methyl isobutyl ketone to obtain an aqueous extract and raffinate, and the extract was washed in a washing system. countercurrent to 4 stages using acid

  purified product as a wash liquor to obtain a

and a spent aqueous wash liquor which has been recycled to the extraction and the release or countercurrent separation step

  two stages with water to obtain a layer of practically

  acid-free, recycled to the extraction and an acid

  It contains 41.2% P 2 O 5, 0.50% SO 3, 40 ppm Fe, 6 ppm Mg, 1 ppm Al, and 0.4 ppm As, which had a pale yellow color. The purification method used was that described in US Pat. No. 3,914,382 with a 65:35 cutoff of P205 between P205.

  in the acid produced and in the raffinate. The color of the acid

  could be improved if necessary by treatment with 1% activated carbon, compared to the 5% of activated

  for a corresponding process employing non-treated rock

  thermally. No phase separation problem was observed, for example formation of very stable emulsions at the solvent / water interface, whereas problems of this kind have been observed.

  during the process using a rock not treated thermally.

  Examples 46 to 48 The wet phosphoric acids prepared in Examples 42 and 44 were each converted to sodium phosphates and then to sodium tripolyphosphates. Each acid was treated to reduce its sulphate and fluoride impurities and reacted with sodium carbonate in a

  Na: P ratio of 5: 3, with filtration of the solids

  to provide an aqueous solution of mixed sodium phosphates with a Na: P ratio of 5: 3, which has been dried and

  calcined for 1 hour to give the sodium tripolyphosphate. The salt of the acid from Example 42 was white, less co-

  the salt obtained from untreated

  is lying. The color can be improved by treating liquors having an Na: P ratio of 5: 3 with up to 0.5% activated carbon, compared with the use of 5% or more of activated carbon for the product obtained from untreated heat-treated rock. The acid salts from Examples 43 and

44 were white.

  Examples 49 to 51 Rocks prepared according to the procedure described in

  Examples 19, 40 and 41 were reacted with chlorinated acid.

  water to 17% in order to form reaction mixtures comprising

  calcium chloride, carbon particles, acid

  phosphoric acid, residual hydrochloric acid and non-organic

  attacked. Each reaction mixture was defluorinated by treatment with a portion of an aqueous suspension of calcium hydroxide

  (equivalent to the F content and a portion of the acid), and

  by separation of the solids and addition of a large amount of the calcium hydroxide suspension (equivalent to most of the acid content to obtain the dicalcium acid phosphate), with separation of the solid dicalcium acid phosphate, suitable for the feeding. Finally, the rest of

  the acid was reacted with a final portion of the suspension.

  calcium hydroxide to obtain a final fraction of

  dicalcium acid phosphate separated from the mother liquor

  taking calcium chloride. The quantities of the suspension of hy-

  calcium hydroxide added in the three steps were

  20, 70 and 10% of the total quantity.

  Examples 52 to 54 Each reaction mixture comprising calcium chloride, carbon particles, phosphoric acid, residual hydrochloric acid, uninjured rock, as obtained in Examples 49 to 51, was filtered. to separate a solid fraction

  including rock and carbon particles, so as to obtain

  finally, an acid liquor. 5 parts by volume of this

  were extracted with 10 parts by volume of a mixture of 8 parts by volume of amyl alcohol and 2 parts of 35% hydrochloric acid to provide an organic phase comprising purified phosphoric acid and acid. hydrochloric acid and

  aqueous acid phase, which have been separated. The phases separated

  done quickly without any interfacial problems. The organizational phase

  was mixed with 2.5 parts by volume of water to release

  acids in order to obtain an organic phase having a

  acid and a mixed aqueous phase containing the acids

  hydrochloric and phosphoric; phases were separated from new

  calf without any interfacial problems. The mixed aqueous phase was heated to evaporate the hydrochloric acid and collect

  purified wet phosphoric acid.

Examples 55 and 56

  In the same way as in Example 45, the human pathway acids

  examples 43 and 44 were concentrated and purified by ex-

  solvent pull with methyl isobutyl ketone and released by

  water to obtain purified aqueous phosphoric acids.

  The concentrated wet acid from Example 43 contains

2476055-

  51.9% P 2 O 5, 1.8% SO 3, 1.36% Fe, 0.9 Mg, 1.0% AI, was purified to give 42.7% P 2 O 5 acid. , 0.54% S03.1-185 ppm Fe, 9 ppm Mg and 12 ppm A1 and a raffinate of 41.3% P205, 2.7% 503, 2.8% Fe, 2 , 0% Mg and 1.9% A1, with a 68:32 cutoff between purified acid and raffinate. The concentrated wet acid from Example 44 contained 56.0% P205, 1.3% SO3, 0.23% Fe and 0.6% Mg and was purified to give an acid containing 40.5% P205, 0.7% SO3, 28 ppm Fe and 10 ppm Mg and a raffinate containing 40% P205, 1.7% SO3, 0.6% Fe and 1.4% of Mg with a 70:30 break between the purified acid and the raffinate. In none of the cases

  problems have arisen due to the production of emulsions

liquid / liquid surface.

  Examples 57 to 59 Rocks prepared according to the procedures described in Examples 19, 40 and 41 were reacted with 24.2 parts

  by weight of nitric acid at 58% for 10.8 parts by weight of rosin

  heat treated Morocco (and corresponding quantities

  for the other 2 rocks) and in each case a

  aqueous mixture of calcium nitrate, coal particles,

  Unexpected rock, phosphoric acid and residual nitric acid.

  Each mixture was filtered to remove carbon particles.

  ne, and / retroqli to 0 C; a solid fraction comprising ni-

  The calcium flux was then separated from the acid-aqueous solution which contained the nitric and phosphoric acids and the nitrate of

  calcium. Each aqueous acid solution was treated with 2.55 parts

  anhydrous ammonia, added continuously. The resulting mixture, which contained nitrate and ammonium phosphate and calcium nitrate, was evaporated to obtain a melted product containing

  from 0.5 to 5% water, which could be used as fertilizer. In each

  that the molten product was mixed with 5.8 parts of chlorine

  of potassium and the mixture was granulated to provide a fertilizer

  compound in a ratio N: P: K equal to 17:17:17.

  Examples 60 to 62 The wet acids obtained in Examples 42 to 44 were concentrated to a content of 54% P205. Each concentrated acid was treated by bubbling a stream of ammonia

  anhydrous to an atomic ratio N: P of 1.35: 1. The temperature

  It rose to 115.degree. C. and water was added so that the suspension obtained remained fluid (approximately 20% of free water). The hot slurry was dispensed onto a bed of fine particles of a recycled ammonium phosphate product and the ammoniation was supplemented with anhydrous ammonia to an N: P atomic ratio of about 1.8. : 1, the recycling ratio was 2.5 parts recycled per 1 part extracted as product. The product at 850C was sent to a dryer and cooler and then granulated for

  give an ammonium phosphate of ratio N: P: K of 18: 47: 0,

prayed as fertilizer.

  Examples 63 to 65 The wet acids obtained in Examples 42 to 44 were concentrated to obtain a 50% P205 acid. 50

  parts of each concentrated acid were mixed with 12.5 parts

  of water and sent to a tank containing a slurry of

  ammonium phosphate. 8 parts of anhydrous ammonia were added

  to obtain a mixture of N: P ratio of 1.3: 1. The water has been

  evaporated to leave a slurry of 80% ammonium phosphate.

  The slurry could be granulated by mixing with the solid product

  recycled, and granulated to form an ammonium phosphate fertilizer

  granulated nium. The slurry was mixed with sodium chloride

  solid potassium and an 80% solution of ammonium nitrate and

  granulated to give a compound fertilizer N: P: K.

Examples 66 to 68

  6.2 parts of each concentrated 50% P 2 O 5 acid used

  Examples 63 to 65 were mixed with 7 parts of a 95% ammonium nitrate solution and 0.8 parts of anhydrous ammonia were then slurried in the mixture. The heat of reaction evaporated the water leaving a concentrated solution of% water which was charged to an evaporator to produce a dry melt. Each melt was mixed with 7.8 parts of potassium chloride and the granulated mixture to form 20 parts.

  parts of a compound fertilizer with a ratio of 15:15:21 N: P: K.

  Examples 69 to 71 6 parts of the heat-treated rocks according to Example 41 (and corresponding amounts of the heat-treated rocks according to Examples 19 and 40) were each ground to obtain

  a powder of which 80% passed through a sieve having an opening

  mesh size of 150 microns. Each powder was mixed with 4.8 parts of 72% sulfuric acid to obtain a slurry which was continuously passed through a drying chamber to provide a solid product which was crushed and stored in a heap for 1 hour.

  week to complete the reaction to form a superphosphate.

  Each superphosphate could be used as fertilizer. Each super

  phosphate was mixed with solid potassium chloride and 80% aqueous ammonium nitrate in the weight ratio of 48: 17: 36, then granulated, cooled and dried to obtain a free-flowing fertilizer having a ratio N: P: K of

5: 10.5: 10.5.

  Examples 72 to 74 In the same way as in Examples 69 to 71, 4.1 parts of

  thermally treated rock according to Example 41 (and quanti-

  of the thermally treated rocks according to Examples 19 and 41) were ground and mixed with 6-8 parts of the wet phosphoric acid containing 50% P 2 O 5 and

  product prepared according to Examples 67 to 69. Each triple superphosphorus

  phate obtained could be used as a fertilizer. Each triple superphosphate was mixed with potassium chloride and

37 2476055

  aqueous solution of ammonium nitrate in the proportions 30:25: 54 and the mixture was converted as above into a fertilizer

  compound, very fluid, having an N: P: K ratio of 15:15:15.

Claims (47)

  1. Process for heat treatment of phosphate rock,   characterized in that a calcium phosphate rock containing organic compounds is heat-treated at a temperature between 380 and 600 ° C for processing at least   part of the organic carbon compounds to form a   heated sheet comprising carbon particles.   2. Method according to claim 1, characterized in that the rock is heated during a continuous passage in at least one zone heated to a temperature between 380 and 6000C and   the heated rock is extracted from said zone.   3. Method according to one of claims 1 or 2, characterized   included in that the rock is heated to a temperature / between 380 and 480C.   4. Method according to one of claims 1 or 2, characterized   in that the rock is heated to a temperature between 460 and 540 ° C.   5. Method according to claim 1, characterized in that the rock does not come from Florida or Egypt if the heating takes place at a temperature between 490 and 5100C, nor from Russia if the heating takes place at a temperature between 490 and 540 C, and   no longer from Utah or Morocco if the heating takes place at a between 540 and 5600C.   6. Process according to any one of claims 1 to 5,   characterized in that the rock is heated in the presence of a gas   comprising molecular oxygen.   7. Method according to any one of claims 1 to 6,   characterized in that the rock comprises a total of 0.05 to 0.4%   organic compounds (expressed as carbon) and organic materials soluble in acids.   8. Process according to any one of claims 1 to 7,   characterized in that the rock contains 30 to 40% P205 and 45 to % calcium (expressed as CaO).   9. Process according to any one of claims 1 to 8,   characterized in that the phosphate rock before heating is   which provides a brown liquid with 27% hydrochloric acid.   10. Process according to any one of claims 1 to 9,   characterized in that the rock originates from Idaho, North Carolina, Tennessee in the United States of America, or Tunisia, Jordan, Algeria, Senegal, Youssoufia in Morocco, Kola,   from Nauru, Oceania or Zin to Israel.   11. A method according to any one of claims 2, 7 or   8, characterized in that the Florida rock is heated continuously for 15 minutes to 2 hours at a temperature of between 450 and 5500C.   12. Method according to one of claims 2 or 8, characterized   in that the rock of Morocco is heated continuously for 15   minutes to 2 hours at a temperature between 380 and 440C.   13. Process according to any one of Claims 1 to 12,   characterized in that the rock contains organic compounds and thermolabile iron sulfide, insoluble in acids, and is   heated to a temperature insufficient to transform the total   acid-insoluble iron sulphide to acid-soluble iron sulphide, and in that a heated rock comprising phosphate rock, carbon particles and   iron sulphide insoluble in acids.   14. Process according to claim 13, characterized in that the rock before heating contains at least 500 ppm of sulphide of   iron insoluble in acids (expressed in S).   15. Heat-treated calcium phosphate rock, pre-   prepared by a process according to any one of claims 1 to 14.   16. Heat-treated calcium phosphate rock,   characterized by carbon particles and practically   no organic compounds that are soluble in acids.   Rock according to claim 16, characterized in that it also comprises heat-labile iron sulphide, insoluble in acids.   Rock according to claim 17, characterized in that   contains at least 500 ppm of said iron sulfide (expressed as S).   19. A rock according to claim 17 or 18,   characterized in that at least 80% of the iron sulphide is insolu-   acid and the remainder is soluble in acids. Process for the preparation of phosphates from a phosphate rock, characterized in that the phosphate rock comprising   carbon particles according to any one of the claims   15 to 19 is reacted with at least one of the phosphoric acid   phoric or sulfuric to form a calcium phosphate fertilizer. 21. The method of claim 20, characterized in that the rock does not come from Morocco or Utah, unless the rock has been heated in a continuous process, or has been heated to a temperature between 380 and 440'C or 460 and 540'C or 560 and 600'C, or unless the rock has been   to react with sulfuric acid or a mixture of sulfuric acid and phosphoric acid.   22. The method of any one of claims 20 or   21, characterized in that the rock has been heated to a temperature of between 460 and 540 OC.   23. Process according to any one of claims 21 or   22, characterized in that the rock and its heating temperatures   are as defined in claims 2, 11 or 12.   24. Process according to any one of claims 20 to 23,   characterized in that the rock comprising carbon particles   is reacted with a quantity of phosphoric acid which   80 to 120% of the amount needed to react with the   to form diacid calcium phosphate or with a quantity   of sulfuric acid which represents 80 to 120% of the quantity required   to react with the rock to form a sulphate mixture   calcium and diacid calcium phosphate.   25. A process for the preparation of phosphoric acid from a phosphate rock, characterized in that the calcium phosphate rock comprising carbon particles, prepared by heating the phosphate rock at a temperature between 380 and 600 ° C,   or the rock according to any one of claims 15 to 19, is   reacted with a mineral acid such as hydrochloric acid, nitric acid or sulfuric acid, to produce a mixture   a calcium salt of the acid, phosphoric acid and particulate   carbon, and in that a solid fraction comprising the particles is separated from the mixture.   26. Process according to claim 25, characterized in that the phosphate rock has been continuously heated according to the process as defined in claim 2.   27. Method according to any one of claims 25 or 26,   characterized in that the phosphate rock is heated to a temperature of   between 380 and 590 ° C, when the acid is only hydrochloric acid.   28. Process according to any one of claims 25, 26   or 27, characterized in that the rock comprising carbon particles is reacted with an equivalent amount of acid   at least 90% of the calcium content of the rock.   29. Process according to claim 28, characterized in that the rock comes from Florida or Morocco and has been heated to a   temperature between 380 and 550 ° C.   30. Process according to any one of claims 25, 26, 28   or 29, characterized in that the acid is at least one of the acids nitric and sulfuric.   31. The method of claim 30, characterized in that the rock comprising carbon particles is reacted with a mixture of sulfuric acid and phosphoric acid to form   a solid fraction comprising calcium sulphate and   carbon, and wet phosphoric acid, and   in that the acid is separated from the solid fraction.   32. Process according to any one of claims 25 to 31,   characterized in that the heated rock comprises thermolabile iron sulfide, insoluble in acids, and the solid fraction comprises carbon particles and insoluble iron sulfide in acids.   33. Process according to any one of claims 25 to 32,   characterized in that after separation of the solid fraction,   the phosphoric acid is treated with an unmodified organic solvent   target to water to produce an organic phase and an aqueous phase   itself, and that the acid is collected from at least one phases.   34. Process according to claim 33, characterized in that the phosphoric acid contains uranium and in that with or without prior concentration of the acid after separation of the solid fraction, it is extracted with a solvent to eliminate at least a portion of the uranium in the organic phase, from   from which a product containing uranium is collected.   35. Method according to one of claims 33 or 34, characterized   in that the phosphoric acid, with or without concentration after the separation of the solid fraction, is extracted with a   organic solvent immiscible with water to obtain a phase   comprising purified phosphoric acid and a diaper   of aqueous raffinate, which are separated, and that the phosphoric acid   phoric is collected from the organic phase in form   phosphoric acid or a salt thereof.   36. Process according to any one of claims 25 to 34,   characterized in that after the separation of the solid fraction and with or without concentration of the acid, the phosphoric acid is treated with at least one nitrogen compound, such as ammonia, in order to   form at least one ammonium phosphate.   37. Process according to any one of claims 25 to 34,   characterized in that after separation of the solid fraction, the phosphoric acid is treated with an alkali to form at least one alkali metal phosphate which is separated from any solids also trained.   38. Process according to any one of claims 25 to 34,   characterized in that after separation of the solid fraction, the wet process acid is mixed with calcium hydroxide   and the precipitated acid calcium phosphate is separated.   39. Process according to any one of claims 20 to 38,   characterized in that the rock has been heated during a pass   continuously in at least one zone heated to a temperature between 380 and 600 ° C and the heated rock is extracted from the or zone (s).   40. Calcium phosphate fertilizer prepared by the process according to   any one of claims 20 to 24 or 39.   41. Liquid mixture comprising a calcium salt and acid   phosphoric acid prepared by the process according to any one of 25 to 30 or 39.   42. Wet phosphoric acid prepared by the process   according to any one of claims 30 to 32 or 39.   43. Phosphoric acid, purified wet process or one of its   seIs, prepared by the process according to any of the claims 33 to 35 or 39.   44. Product comprising uranium, obtained by the process   according to any one of claims 34 or 39.   45. Ammonium phosphate prepared by the process according to   any of claims 36 or 39.   46. Alkaline metal phosphate, prepared by the process according to   -one of claims 37 or 39.   47. Acid calcium phosphate prepared by the process according to   any of claims 38 or 39.