CS273034B1 - Method of cobalt-copper double cyclo-tetraphosphates high-temperature preparation - Google Patents

Abstract

The invention is based on the calcination of the initial mixture composed of compounds of the cupric and cobaltous type of dihydrogen-phosphates, or initial mixtures of phosphoric acid with cupric or cobalt hydrogen-phosphates or phosphates, or with copper or cobalt oxide, hydroxide, carbonate or hydrogen-carbonate in quantities corresponding to the molar ratio Co/Cu = (2-x)/x and P2O5/(Co+Cu) equal to 0.99 to l.l to temperatures higher than 1060 degrees C, when melting occurs. By intensive cooling this is transformed into a vitreous intermediate product, which, by repeated heating to a temperature of at least 560 degrees C and lower than 870 degrees C, re-crystallises causing the occurrence of micro-crystals of cobalt-copper double cyclo-tetraphosphates.

Description

BACKGROUND OF THE INVENTION The present invention relates to a high-molecular-weight process for the preparation of double cobalt-ammonium cyclo-tetraphosphates.

Double cyclo-tetraphosphate cobalt-exchange formula C ^"Co 2-x ^P 4 ° L2 ^'x (O, 2) are compounds of the type of cyclic condensed phosphates · aniontam, consisting of four interconnected tatraedry (PO ^). The aodroflall compounds with high thermal and chemical stability with a crystal structure in a monoclinic system are desired. The present inventors disclose these compounds as novel materials and further suggest a method for their synthesis based on the tarmic treatment of a mixture of cobalt and copper (II) cobalt and copper (II) carbonate and phosphoric acid, using only temperatures where the product has not yet melted - ie up to 870 ° C. The process is advantageous from an energy and technological point of view, but sometimes it is necessary to prepare products with regular particles. microcrystals formed well developed COG-C-X C and from ^{0 to} J-P ^{ro nS sou} to ^{the TE <E} Using preferred. These are, for example, the use of products for experimental research work, for preparative purposes and also for some agrochemical uses.

Preparation of Product with the above particle properties umožňuje.podle high žpůáob invention for preparing double -cyclopentane-cobalt-tetrapolyphosphate měňnatých formula ^C - ^ ^and ^ 2_x ^u x ^P 4 ° i2> where x (0} 2) is characterized by a starting mixture Consisting of cobalt and cuprous dihydrogen phosphates, hydro-phosphates, phosphates or oxides, oxides, hydroxides, carbonates or hydroxides, in such quantities that the solar ratio Ce / Cu corresponds to (2-x) / x and, on the other hand, phosphoric acid in such quantities they are heated to divalent cations in eae at a molar ratio P ^ q / / (Co + Cu) of 0.99 to 1.1, preferably 1 to 1.01, preferably such that the heating rate is less than 20 ° C / min and Tanzi steam calcination in the space is 60 to 100 kPa, to a temperature greater than 870-®C, preferably than about 1060 C ^e, ever resulting intermediate melt and then the melt is cooled, preferably by pouring it into water or a cold plate of inert material, to form another intermediate product in the form of a homogeneous amorphous glassy material, which ee preferably after grinding, is reheated to a temperature of at least 560 ° C and less than 870 ° C, preferably to a temperature higher than 700 ° C and lower than 800 ° C, when recryetalization of the intermediate epol and rearrangement of tetraadrates (PO4) in the anion to form double cobalt tetanaphosphates occurs, which is finally and advantageously pulverized into forms of fine-grained particles of acrocryetal character.

In the high-temperature process for the preparation of cobalt-ammonium double-cyclophosphate, it is possible to start from raw materials in which the content of phosphorus anions and associated divalent cations, expressed as a molar ratio P ₂ O _g / (Co + Cu) is equal to or 0.99 to 1.1, preferably 1 to 1.01. It is therefore possible to start from a mixture of dihydrogenphosphates (dihydrates or anhydrates) or a mixture of hydrogenphosphates or phosphates (tertiary) (again in a hydrate or anhydride farm) and phosphoric acid. Phosphate-type feedstocks, however, are less suitable for wider technological applications because they require a pre-preparation which is not a simple operation in itself, so that it is more suited to producing smaller quantities of c-Co _2-x Cu _x P 2 O ₂ completely pure form. For technological applications such as the synthesis of double cyclotetraphosphates for pigmentary or agrochemical purposes, it is preferable to precipitate from a mixture of oxides or hydroxides, carbonates or cobalt and cupric hydroxide-carbonates (or mixtures thereof) and phosphoric acid. The acid can be used at any concentration, but it is to be counted that, in view of the effective reaction of the starting mixture, the more preferred acids are more dilute, whereas in terms of energy requirements for evaporating diluting water from the acid, higher acids are more suitable. The acid concentration should therefore be selected individually depending on the reactivity of the starting cobalt and acacia compounds and according to the manufacturer's energy possibilities *. When using acid

CS 273 034.Bl high concentration can create a risk of sanoetic condensation of phosphoric acid to higher polyphosphoric acids at high heating rates and even phosphorus pentoxide at high temperatures, which can then volatilize from the mixture such an unfavorable ratio of phosphate anions and bivalent cations in the mixture calcine and melt, respectively. The first intermediate type of condensed formate formed during calcination is dihydrogen diphosphate at temperatures of about 200 ° C. He then. at temperatures of about 100 to 200 higher, it is converted to a product which, to a greater or lesser extent, corresponds to the double cobalt tetrachlorophosphate. In order to maximize the proportion of double cyclo-tetraphosphates, which are also an intermediate in this phase, and to minimize the risk of separate condensation of the phosphorous component and hence its volatilization losses, it is advantageous to conduct a heating rate of less than 20 ° C / min. water vapor and pressures of 60 to 100 kPa Maintaining a water vapor pressure in the calcite space of at least 60 kPa is advantageous to prevent the formation of undesirable by-products, in particular to prevent cleavage and separate condensation of the phosphoric bed. The water vapor present in the individual condensation reaction slows the formation of intermediates somewhat; enables their more quantitative course; it also avoids the formation of undesired non-porous crusts on the surface of the particles in the calcined mixture to prevent dehydration reactions. The final calcination temperature at this stage of the preparation of the product of the invention must be above 870 ° C because this is the lowest temperature when some intermediates melt. Because of the need for rapid melting of the calcine, which may also include other starting materials, it is preferred to select a temperature of at least 1060 ° C. The intermediate melts non-congruently, with the disintegration of the tetraphosphate cycles and the coupling of the resulting short phosphate chains into long chains, to which the presence of at least trace amounts of water vapor in the melt area also contributes. Thereafter, the melt needs to be quenched, preferably by pouring it into water or onto a cold plate of inert material (metal or ceramic). This results in a delimited intermediate which is a homogeneous amorphous mass of glassy character, containing long-chain anions. The piece of glass obtained in this way, after cooling and, if necessary, after cooling. preferably dry dry and reheated to recrystallize the intermediate to rearrange the tetrahedra (PO ₄ ) in the anion to form cobalt-cobalt-double-cyclo-tetrachloride microcrystallines of the formula ^c 2 ^Co x-x ^Cu x ^p 4 ° 12 ² )) · This releases small amounts of water bound chemically in the glassy intermediate. Therefore, it is easier to conduct the thermal recrystallization process when the glassy intermediate product is dry ground. The lower temperature of this reheating is 560 ° C and corresponds to the lowest recrystallization temperature of the cobalt intermediates. While this temperature can only be achieved because the recrystallization process is exothermic and once it has started running spontaneously, the preferred temperature range for recrystallization is temperatures above 700 ° C and below 800 ° C, where recrystallization of the glassy intermediate does not always occur at any heating rate and any consistency of the intermediate (powdered, lumpy or completely compact) and there is no risk of melting the finished product, which would again lead to the formation of a glassy intermediate due to the unconventional properties. It is therefore not possible to exceed the limit of 870 ° C during rocrystallization, which corresponds to the lowest melting point of the double cyclotrophosphate. The final products - cobalt-copper (II) -cyclo-phosphate double-phase - after cooling, are advantageously further comminuted (grinding, comminution) to a regular, microcrystalline-like, particulate particle. If the glass product was ground before recrystallization, the final grinding of the products is very easy.

The process according to the invention further comprises treating the product after the kaleinael with hydrochloric, sulfuric, nitric or phosphoric acid, preferably a concentration of 0.5 to 10% by weight. This operation is carried out as an eventual purification of the obtained products in their pure form, for example for analytical or preparative purposes. The action of said acids removes any unwanted byproducts 1 or possibly residues of the starting mixture, which thus become dissolved. Double cy3

CS 273 034 B1 Cobalt tetraphosphates cobalt tetrachlorides resist these acids.

Advantages of the process according to the invention are the high yield and 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 surface command well developed. 3eou are therefore suitable for some special applications.

Examples of use of the process according to the invention are given below.

Example 1

A mixture of 100 g hydrogenfosforačnanu cobalt (45.8% P ₂ 0 _5, ³⁸ ° ^C X) ^and g hydrogenfooforečnanu aěSnatého (44.8% ^P 2 · ³⁹ ° with ^«8 × ^Cu) with ee 150 g of phosphoric acid by weight. concentration of 85% ^H 3 ^P0 4 Hýla kelcinovana at 12 ° C / min while being TENZA water vapor in the calcination chamber is maintained at temperatures up to 500 ° C higher than 85 kPa at a temperature of 1100 ° C. The resulting melt was quenched by pouring into water. The obtained glassy intermediate was separated and dried and aucha ground. It was then heated to 700 ^e C and PE triturated cool. The product contained 96.5% of cobalt-copper (II) c-CoCuP2O4 double cyclo-tetraphosphate, and 230 g was obtained as regular fine crystals.

Example 2

A mixture of 100 g of cobalt carbonate (49% Co) and 103.6 g of cupric carbonate (51% Cu) together with 830 g of phosphoric acid at a concentration of 40% ^ 3 ^ 4 was combined at a rate of 10 ° C per minute, the vapor in the calcine compartment was maintained at a temperature of more than 80 kPa, at a temperature of 1100 ° C., to a temperature of 1100 ° C. The resulting melt was quenched by pouring onto a corundum plate. after allowing to cool triturated. 8ylo give 367 g of a product containing more than 98,5% of double-cyclo tetřafosforečnenů cobalt-mě3natýoh formula C-5 ^Cu by ^NAV-5-P 4 ^{8 12 R} lkrokrystalické finely divided form.

Claims (2)

SUBJECT OF THE INVENTION 1. A process for preparing a high-temperature double-cyclo tetrafoeforečnanfi cobalt-aě3natých formula C "2_x ^{Cd Cu} x ^P 4 ° 12 'x ^ (OU 2), characterized in that the starting mixture consists .mu.Ci secondly dlhydrogenfoeforečnanů, hydrogenfeeforečnanů, phosphates or oxides, of cobalt and cupric hydroxides, carbonates or hydroxides of carbonate in such quantities that the molar Co / Cu ratio corresponds to (2-x) / x and on the one hand from phosphoric acid in such an amount that the phosphorus anonts are small and PgOg relative to divalent cations (ICo + Cu) equal to 0.99 to 1.1, preferably 1 to 1.01, that it heats, preferably such that the heating rate is less than 20 ° C / ml and the water vapor tan in the calcine space is 40 up to 100 kPa, to a temperature higher than 870 ° C, and preferably higher than 1060 ° C, when the previously formed intermediates melt and then melt quench, preferably by pouring into water or on a cold plate from an inert material, to form another intermediate product in the form of a homogeneous amorphous glassy material which can be, preferably after grinding, reheated to a temperature of at least 560 ° C and less than 800 ° C when recrystallization of the intermediate together with the tetraodere rearrangement (PO) In the anion, double cobalt (II) -cobalt copper (II) cyclophosphates are formed which are finally and preferably comminuted to form fine-grained particles of microcrystalline nature. Method according to claim 1, characterized in that the product after calcination is treated with hydrochloric, sulfuric, nitric or phosphoric acid, preferably a concentration of 0.5 to 10% by weight.