CS266699B1 - High-temperature method of double cobalt-nickel cyclo-tetraphosphates preparation - Google Patents

Abstract

The solution lies in calcining the east of a mixture consisting of a combination of cobalt and nickel-type dihydrogen phosphates, respectively. mixtures of phosphoric acid and hydrogen phosphate with cobalt and nickel phosphates or with phosphates, hydroxides, hydroxides of carbonates or carbonates of cobalt and nickel in amounts corresponding to the molar ratio Co / Ni «(2-x) / and P205 / (Co + Ili) equal to 0.97 to 1.15, at temperatures above 1060 < 0 > when the melt is formed. This is converted to a vitreous intermediate by quenching, recrystallizing to at least 500 [deg.] C. and less than 1060 [deg.] C., recrystallizing to form double microcrystalline alumina nickel cobalt cyclo-phosphates.

Description

The present invention relates to a high temperature process for the preparation of double cobalt-nickel cycloetraphosphates.

Double cobalt-nickel cyclo-tetraphosphates c- ^ Og ^ Ni ^ P ^ O ^, where x (Oj 2) are compounds of the condensed phosphate type with a cyclic anion, formed by four interconnected tetrahedra (PO ^). These are colored compounds with high thermal and chemical stability with a crystal structure in a monoclinic system. The present invention discloses these compounds as novel substances and further proposes a process for their synthesis which is based on the heat treatment of a mixture of cobalt and nickel oxide, hydroxide, carbonate or hydroxide-carbonate and phosphoric acid, only temperatures where the products have not yet melted - ie up to 1060 ° C. The method is advantageous from an energy and technological point of view, but sometimes it is necessary to prepare products with regular particles formed by well-developed microcrystals ^ COg ^ Ni ^ P ^ O. ^, which are more advantageous for some applications. work, for preparative purposes and also for some agrochemical and pigmentary uses.

Preparation of the product with the above properties of particles and higher purity of the present invention allows high temperature process for preparing double-cyclo tetrapolyphosphate cobalt-nickel, the formula ^C ^ ™ _X ° 2 ^{'of the Ni} x ⁰ 4 ^{where x} i2 * & (° »2), and

- 2,266,699, characterized in that the starting mixture consists on the one hand of cobalt and nickel dihydrogen phosphates, hydrogen phosphates, phosphates or oxides, carbonates or hydroxide carbonates in such amounts that the Co / Ni molar ratio corresponds to (2-x) / x and on the other hand from phosphoric acid in such an amount that the phosphorus anions are in the molar ratio PgO 2 (ACo + Ni) equal to 0.97 to 1.15, preferably 1 to 1.02 to the divalent cations in the mixture, preferably heated so that the rate heating is less than 25 ° C / min and the water vapor pressure in the quenching space is 40 to 100 kPa, to a temperature higher than 1060 ° C, preferably higher than 1250 ° C, when the previously formed intermediates melt and then the melt is rapidly cooled, preferably by pouring into water, or the cold plate of an inert material to produce the next product in the form of a homogeneous amorphous matrix glass which is further _f preferably after grinding again heated to a temperature of at least 500 ° C and lower than 1060 ° C, preferably to temperature higher than 750 ° C and lower than 950 ° C, when recrystallization of the intermediate occurs together with rearrangement of tetrahedra (Ρθ ^) in the anion, to form double cobalt-nickel cyclophosphates, which are preferably finally comminuted into fine-grained microcrystalline particles .

In the high-temperature process for the preparation of double cobalt-nickel cyclophosphates, it is possible to start from raw materials in which the content of phosphorus anions of the respective divalent cations is expressed by a molar ratio P ₂ 0 $ / / (Co + Ni) equal to one or is close to one 0, 97 to 1.15, preferably 1 to 1.02. It is therefore possible to start from a mixture of dihydrogen phosphates (hydrates or anhydrides) or from a mixture of hydrogen phosphates or phosphates (tertiary) (again in hydrate or anhydride form) with phosphoric acid. Starting materials of type phosphates are, however, wider technological use less desirable, as they require preparation in advance, which in itself is not a simple Opera- 3266699 crayfish, so it is suitable for the preparation of only rather small quantities of products e «_ ° _{2 x} ^O NV4 ₁₂ v® in a completely pure form.

For technological use, it is more advantageous to start from mixtures of oxides, hydroxides or hydroxide-carbonates or cobalt and nickel carbonates with phosphoric acid. The acid can be used in any concentration, but it is to be understood that from the point of view of efficient reaction of the starting mixture, dilute acid is more preferred, while from the point of view of energy requirements for evaporation of diluting water from acid, higher concentration acid is more suitable. The acid concentration must therefore be chosen individually according to the reactivity of the starting cobalt and nickel compound and according to the energy possibilities of the possible manufacturer. When high concentrations of acid are used, there is a risk of condensation of phosphoric acid separately to higher polyphosphoric acids at high heating rates and even to phosphorus oxide at high temperatures, which can then flow out of the mixture and adversely affect the ratio of phosphate anions to divalent cations in calcine. resp. melt. The first condensed phosphate-type intermediate to be formed during calcination is double dihydrogen diphosphate, at temperatures around 200 ° C. At the temperatures of about 100 to 200 ° C higher, it then changes to a product which corresponds to a greater or lesser extent to double cyclo-tetraphosphates. In order to maximize the proportion of double cyclophosphates, which are also intermediates at this stage, and to minimize the risk of condensation of the phosphorus component itself, and thus its volatile losses, it is advantageous to heat at less than 25 ° C / min in the presence of water vapor with a tension of 40 to 100 kPa. Maintaining a water vapor pressure in the calcine space of at least 40 kPa is advantageous for preventing the formation of undesired by-products, in particular for preventing the cleavage and separate condensation of the phosphorus component. The presence of water vapor slows down the formation of intermediates somewhat by condensation, allowing them to proceed more quantitatively; it also prevents the formation of undesired non-porous crusts on the surface of the particles in the calcined mixture, which would prevent the course of dehydration reactions. Final calcination temperature

266,699 at this stage of the preparation of the product according to the invention must be higher than 1060 ° C, as this is the lowest temperature at which the respective intermediates melt; Due to the requirement for rapid melting of the calcine, which may contain other higher melting substances, it is advantageous to choose a higher temperature, i.e. 1250 ° C. the presence of at least trace amounts of water vapor in the melt space also contributes. The melt must then be quenched, preferably by pouring into water or on a cold plate of inert material (metal or ceramic). This gives another intermediate, which is a homogeneous amorphous mass of glassy character, containing anions in the form of long chains. The lumpy mass thus obtained is, after cooling and eventually drying, preferably ground dry and reheated so as to recrystallize the intermediate to rearrange the tetrahedra (PO4) in the anion, to form microcrystals of double cobalt-nickel cyclophosphates of the formula θ- θ ^ -χ ^ Λ-θΙ2 ^e (° »2)), small amounts of chemically bound water are released in the glassy intermediate. Therefore, it is easier to guide the thermal recrystallization process if the glassy intermediate is dry ground beforehand. The lower temperature limit of this reheating is 500 ° C and corresponds to the lowest recrystallization temperature of the cobalt-nickel intermediates. Although this temperature only needs to be reached, since the recrystallization process is exothermic and as soon as it starts, it continues to run spontaneously, but the preferred temperature range for recrystallization is above 750 ° C and below 950 ° C, with recrystallization of the glassy intermediate always occurring at any time. heating rate and any consistency of the intermediate product (powder, lump or completely compact) without the risk of melting of the final product, which, due to its non-congruent nature, would again lead to the formation of a glassy intermediate product. It can not therefore exceed the recrystallization at 1060 ° C, which corresponds to the lowest melting point binary products, namely, mp 12 ^C ~ ^{Go »x} ^ · ° ^K onečné products bivalent cyclo-tetraphosphate cobalt-nickel - after

- 5 266 699 the cooling is preferably further comminuted (by grinding, trituration) into regular single-grained particles of microcrystalline character. If the glassy product has been ground before crystallization, the final grinding of the products is very easy.

The essence of the process according to the invention further lies in the fact that the product after treatment is treated with hydrochloric, sulfuric, nitric or phosphoric acid, preferably with a concentration of 0.5 to 10% by weight. The operation is carried out as an ev, purification of the obtained products when they are needed in a completely pure form, eg for analytical or preparatory purposes. The action of these acids removes all undesirable by-products, even ev. residues of the starting mixture, which thus go into solution. Double cobalt nickel nickel cyclophosphates resist the action of these acids.

The advantages of the process according to the invention are the high yield and the high purity of the products, which can be further purified by leaching. ^A further advantage of the fine grained nature of microcrystalline particle products that are pi * avidelné surfactant and well developed. They are therefore suitable for some more special uses.

The following are examples of the use of the process according to the invention.

Example 1

A mixture of WO g of cobalt hydrogen phosphoronate (45.8% P ₂ O $, 38% Co) and 99.6 g of nickel hydrogen phosphate (46% Ρ ₂ ° 5> 38% Ni) together with 215 g of phosphoric acid by weight 60% H 2 The PO 2 was calcined at a rate of 15 ° C / min, while the water vapor pressure in the calcine space was maintained at a temperature of 500 ° C higher than 85 kPa, at a temperature of 1250 ° C. The resulting melt was quenched by pouring into water. The resulting glassy intermediate was separated, dried and dry milled. It was then heated to 750 ° C and triturated after cooling. The product contained 98.4% of double cobalt-nickel cyclophosphates of the formula c-CoNiP2 O · ^ and gave 282 g; was in the form of regular fine microcrystals.

Example 2

A mixture of 100 g of cobalt carbonate (49% Co) and 33.9 g of nickel carbonate (48% Ni) together with 440 g of phosphoric acid having a concentration of 50% H 2 PO 2 was calcined at a rate of 10 ° C / min while the water pressure was vapors in the calcine space are maintained up to a temperature of 450 ° C higher than 80 kPa, at a temperature of 1200 ° C. The resulting melt was quenched by pouring onto a corundum plate. The cooled glassy intermediate was dry ground and then heated to 700 ° C and triturated after cooling. 245 g of product were obtained which contained more than 98% of double cobalt-nickel cyclophosphates of the formula c-Co ^ $ Ν1θ 5 ^ 0 in microcrystalline fine form.

Example 3

A mixture of 50 g of cobalt hydroxide carbonate (containing 57% Co) and 157.7 g of nickel hydroxide carbonate (containing 54% Ni) together with 450 g of phosphoric acid with a concentration of 85 wt.% H3PO4 was calcined at a rate of 12 ° C / min. and the water vapor pressure in the calcine space was maintained up to a temperature of 430 ° C higher than 75 kPa, at a temperature of 1280 ° C. The resulting melt was quenched by pouring into water. The resulting glassy intermediate was separated, dried and dry milled. It was then heated to 780 ° C. 425 g of product were thus obtained, which contained 98.7% of double cobalt-nickel cyclophosphates of the formula ο-Oοθ ^ Ni ₁ $ Ρ ^ 0 ₁₂ in microcrystalline form.

Claims (2)

OBJECT OF THE INVENTION A high-temperature process for the preparation of double cobalt-nickel cyclophosphophosphates of the formula ο-Οο ₂ _ _χ Νί _χ Ρ ^ 0 ₁₂ , wherein x <e (0j2), characterized in that the starting mixture consists on the one hand of dihydrogenphosphates, hydrogenphosphates, of phosphates or oxides, hydroxides, hydroxide-carbonates or cobalt and nickel carbonates in such amounts that the Co / Ni molar ratio corresponds to (2x) / x and from phosphoric acid in such an amount that the phosphorus anions are divalent to the divalent cations in the mixture in a molar ratio P ₂ O 8 / (Co + Ni) equal to 0.97 to 1.15 _z , preferably 1 to 1.01, is preferably heated so that the heating rate is less than 25 ° C / min and tension of water vapor in the area of calcination is from 40 to 100 kPa, at a temperature higher than 1060 ° C, _of preferably greater than 1250 ° C when previously formed intermediates melt and then the melt is quenched, preferably by pouring into water, or the cold plate from inert material, to give the next intermediate as a homogeneous amorphous mass of glassy character, which is further preferably reheated after grinding to a temperature of at least 500 ° C and lower than 1060 ° C, preferably to a temperature higher than 750 ° C and lower than 950 ° C, when recrystallization of the intermediate occurs together with rearrangement of tetrahedra (PO 2) in the anion to form double cobalt nickel cyclophosphates, which is finally preferably ground into fine fine microcrystalline particles, 2. The process according to item 1, characterized in that the product after treatment is treated with hydrochloric, sulfuric, nitric or phosphoric acid ₍ preferably by weight concentration 0.5 to 10% by weight).