SU994458A1 - Process for producing fodder and fertilizer phosphates - Google Patents

Description

cyclic mode with pulsating air supply, first with an excess factor of 0.80-0.95, and then with an excess factor of 1.05-1.20, the cycle repeats in 1-35 minutes. It is advisable to enter the retour and the mixture in the amount of 1.5-8%. The essence of the method is as follows. The burning of fluorapatite in the products of burning of fuel containing water vapor is accompanied by a reorganization of the structure of fluorapatite into the structure of tricalcium phosphate. This transition is carried out through the liquid phase, from which the reaction products crystallize. The process of crystallization of a new phase is limited by the rate of formation of crystallization centers. When using a retur containing a new phase of tricalcium phosphate, the activation barriers necessary for the formation of crystallization centers are removed, so that the introduction of the retur accelerates the formation of a new phase. The appearance of the direct intermediate liquid phase, which provides an ideal contact between the initial and final phase of the reaction product, is significant in the reaction rate solid + solid at high temperatures. The appearance of the liquid phase in phosphate systems is determined by the concentration

The time of change is reestablished.

0.5 per oxidant. Burn, MtiH

40

35

thirty

10 oxygen in a gas atmosphere. In the absence of oxygen in the gas phase, the activity of oxygen in the solid phase of oxides increases, as a result of which the mobility of the structural elements of the crystal lattice increases and, as a consequence, the appearance of the liquid phase. However, prolonged firing of phosphates in a reducing atmosphere (air excess factor of 0.8 - 0.95) leads to accumulation of the liquid phase and the formation of goats in the reactor. But the liquid phase, the acceleration of solid-phase reactions, slows down the reactions of solid + gas, transferring them to the diffusion regime. It is known that water vapor desfluorination of fluorapatite is a typical case of solid + gas reaction. In order to maintain the rate of defluorization at a given level, it is necessary to ensure the crystallization of the liquid phase. To simultaneously provide solid + solid and solid 4 + gas firing reactions, it is necessary to carry out firing in a reducing and oxidizing atmosphere with different cycle times. Experimental studies revealed the optimal cycle change time. The results of the experiments are given in table. 1. Kovdorsky apatite was taken as a phosphate raw material for all experiments. Table

Completion time of solid 2, 5 dophase reactions, h

Completion time 1, 8

fluorinated, h

RjOj content in

27.7 finished product,%

As can be seen from the table. 1, the opt.maximum, cycle change time is 1-35-min. As the time decreases below 1 minute, the completion time of solid-phase reactions increases; which leads to a decrease in the content of Pa.O5 in the product, and an increase in the cycle change time by more than 35 minutes significantly increases the time

0.25

0.5

1.0

1.9

ten

3.5

2.5

2.2

26,8

36.2

37.0

36.8

the completion of the obesfluoro1 a-1 processes does not, and thereby either increases the total process time or makes it impossible to obtain a feed product.

. 2 illustrates the feasibility of introducing into the mixture a reconstructed amount of 1 / 5-8%.

Claims (2)

Claim 1. A method of producing feed and fertilizer phosphates by mixing phosphate raw materials with metal oxides and acidic calcium phosphates, followed by granulation of the obtained product in the presence of phosphoric acid and firing in an air atmosphere, characterized in that, in order to intensify the process while maintaining the quality of the product, Retur is used as calcium phosphate, firing in a cyclic mode with a pulsating air supply, first with an excess coefficient of 0.80-0.95, and then an excess of 1.05-1.20, after 1-35 minutes. 2. The method according to p. 55; in an amount of 1.5-8%.