CS267049B1 - High-temperature method of double manganese-nickel cyclo-tetraphosphates preparation - Google Patents

Abstract

The solution lies in starting calcination mixtures consisting of manganese compounds and nickel-type dihydrogen phosphates, resp. phosphoric acid mixtures with hydrogen phosphates or phosphates manganese and nickel or. \ t with oxides, hydroxides or carbonates manganese and nickel in amounts corresponding moles. ratio Μη / Ni = = (2-x) / x and P-O, - (Mn + Ni) equal to 0.97 to 1.15 at temperatures above 950 ° C, when the melt is formed. The one is sharp by cooling it to a vitreous intermediate, which is, by reheating to temperature of at least 460 ° C and less than 950 ° C ° C crystallized to form microcrystals double-cyclo-tetraphosphates manganese-nickel.

Description

microcrystalline character. If the glassy product has been ground before recrystallization, 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 weight concentration of 0.5 to 10%. This operation is performed as ev. purification of the obtained products when they are needed in a completely pure form, eg for analytical or preparative purposes. The action of these acids removes all undesirable by-products, even ev. residues of the starting mixture, which thus go into solution. Double manganate-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. Another advantage is the microcrystalline fine-grained character of the product particles, which are regular and very well developed on the surface. They are therefore suitable for some more special uses.

Example 1

A mixture of 100 g of manganese hydrogen phosphate (47% P at a rate of 10 ° C / min, while the water vapor pressure in the calcine space was maintained up to a temperature of 480 ° C higher than 85 kPa, to 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 680 ° C and triturated after cooling. The product contained 98.5% of cyclo-double tetrapolyphosphate a manganese-nickel-MnNiP formula C ^ Oyg ^and it was obtained 269 g; was in the form of regular fine microcrystals.

Example 2

A mixture of 100 g of manganese carbonate (47% Mn) and 34.9% of nickel carbonate (48% of Ni) together with 347 g of phosphoric acid, a concentration of 65% H 2 PO 2, was calcined at a rate of 5 ° C / min and the tension was water vapor in the calcinate space is maintained up to a temperature of 500 ° C higher than 80 kPa, at a temperature of 1300 ° C. The resulting melt was quenched by pouring onto a corundum plate. The cooled glassy intermediate was dry ground and then heated to 630 ° C and triturated after cooling. Was obtained 249 g of a product containing more than 98% of double-cyclo tetrapolyphosphate manganese nickel formula C-Mn-jNÍq 5P4O12 ^ks and ^{ata krolcr} y if s ^{glass, alumina} fine form.

Example 3

A mixture of 50 g of manganese oxide (containing 77% Mn) and 232.9 g of nickel hydroxide carbonate (containing 53% Ni) together with 740 g of phosphoric acid with a concentration of 75 wt. % H The resulting melt was quenched by pouring into water. The obtained glassy intermediate was separated, dried and ground to dryness. It was then heated to 700 ° C. 611 g of product were thus obtained, which contained 99% of double manganese-nickel cyclotranephosphates of the formula c-Niηθ ^ Ni ^ 5 ^ 4 ^ 2 ^{in the} form of rococrystalline form.

CS 267 049 For years, a higher concentration of acid is more suitable for evaporating the rinsing water from kyaelin. The acid concentration must therefore be chosen individually according to the reactivity of the starting manganese and nickel compounds and according to the energy possibilities of the possible manufacturer. When high concentrations of acid are used, there may be 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 may then flow out of the mixture and adversely affect the ratio of phosphate anions to divalent cations in calcine. ,. reap, 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 minimize the proportion of double cyclo-tetraphosphates, which are also intermediates at this stage, and to minimize the risk of condensation of the phosphorus component itself and thus possible volatilization losses, it is advantageous to heat at less than 10 ° C / min in the presence of water. steam 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 individual condensation reactions somewhat to the formation of intermediates, allows their more quantitative course; 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. The final calcination temperature at this stage of the preparation of the product according to the invention must be higher than 950 ° C, which is not the highest temperature at which some of the relevant intermediates melt; Due to the requirement for fast and reliable melting of the calcinate, which may also contain higher melting substances, it is advantageous to choose a higher temperature, i.e. above 1250 ° C. The intermediate melts non-congruently, with the decomposition of the tetraphosphate cycles and the joining of the formed short phosphate chains into long chains, to which 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 (PO 2) in the anion, to form microcrystals of double manganese-nickel cyclophosphates, of formula ^{c -Mn} 2-x ^N ^ _x ^P 4 ^O i2 / x č (0; 2) /. This releases small amounts of chemically bound water 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 460 ° C and corresponds to the lowest recrystallization temperature of the manganese-nickel intermediates.

Although this temperature only needs to be reached, the recrystallization process is exothermic and once it starts, it continues to run spontaneously, but the preferred temperature range for recrystallizers is higher than 600 ° C and lower than 900 ° C, where recrystallization of the glassy intermediate always occurs at any heating rate and any consistency of the intermediate product (powder, lump or completely compact) and there is no 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 is therefore not possible to exceed the limit of 950 ° C during recrystallization, which corresponds to the lowest melting point of double products, namely the melting point ο-Μ ^ - ^ ΝϊχΡ ^ Ο ^, when x approaches 0. The final products - double manganese-nickel cyclophosphates - are after cooling, it is preferably further ground (by grinding, trituration) into regular fine-grained particles.

Claims (2)

• Ρ δ Ε D Μ Š Τ OF THE INVENTION A process for the high-temperature preparation of double manganate-nickel cycloetraphosphates of the formula c-Mn "Ni PO", wherein x 6 (0; 2), characterized in that the starting mixture consists on the one hand of dihydrogenphosphates, hydrogenphosphates, phosphates or oxides, of manganese and nickel hydroxides or carbonates in such amounts that the molar ratio Μη / Ni corresponds to the relation (2-x) / x and on the one hand from phosphoric acid in such an amount that the phosphorous anions are in mol. a PgO 2 / (Mn + Ni) ratio of 0.97 to 1.15, preferably 1 to 1.04, is heated, preferably so that the heating rate is less than 40 ° C / min and the water vapor pressure in the space of calcine is 40 to 100 kPa, to a temperature higher than 950 ° C, preferably higher than 1250 ° C, where the previously formed intermediates melt and then the melt is rapidly cooled, preferably by pouring into water or on a cold plate of inert material, to form another intermediate in the form of a homogeneous amorphous mass of glassy character, which is further heated, preferably after grinding, to a temperature of at least 460 ° C and lower than 950 ° C, preferably to a temperature higher than 600 and lower than 900 ° C, when recrystallization of the intermediate together with the rearrangement of tetrahedra (P0 ₄ ) in the anion to give double manganetonickel cyclotriphosphates, which is finally preferably ground into fine-grained 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 1C Ϊ-