SU1281555A1 - Method of monitoring degree of defluorination of feed phosphates - Google Patents

Abstract

The invention relates to a method for controlling the degree of defluorization of feed phosphates, can be used in the chemical industry and allows for the continuity of control. The concentration of fluorine in phosphorites is measured by sensor (D) 18, and in the combustion products at the output of the energy technological apparatus 1 and in fluorinated water - by the flow rate of the buffer solution in the measuring cell (electrodes 5, measuring instrument 7, regulator 8, associated with the valve 9 on the line of the buffer solution). The degree of defluorization of the feed phosphate melt is determined using a meter 20. 1 Cp. f-ly, 1 ill. (/)

Description

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The invention relates to methods for controlling the processes of thermochemical defluorization of feed phosphates in heat engineering apparatus, for example cyclone units and rotary kilns, and can be used in the chemical and other related industries.

The aim of the invention is to ensure continuity of control.

The drawing shows a schematic diagram of the implementation of the proposed method.

The technological part of the scheme includes an energy technological apparatus 1 for defluorising feed phosphates, a granule chute 2 for transporting molten feed phosphate to the granbasin 3. The fluorine content meter has a flow measuring cell 4 in which electrodes 5 are placed (fluoride selective and comparison electrode) and to which piping for supplying the buffer solution and the analyzed combustion products through the bubbling device 6.

Electrodes 5 are connected by an electrical circuit with a measuring device 7 and a regulator 8 connected to control valve 9 on the buffer solution line.

The flowmeter 10 and the controller 11 are connected to the control valve 12 to measure and regulate the combustion products flow, and the flowmeters 13 and 14 are used to determine the flow rate of the buffer solution.

For the implementation of the method of controlling the concentration of fluorine in water, a similar measuring cell is provided, which is supplied with ° water that cools the water.

fodder phosphate feeds and a part of fluorine that is selected from them.

To convert signals by the consumption of buffer solutions into signals of the concentration of fluorine in the combustion products Cj (and fluorinated water Cy2, functional converters 15 and 16 are provided, respectively.

For estimating the total concentration of fluorine in fluorinated water and combustion products, an adder 17 is provided, and to determine the difference between the concentration of fluoride in phosphorites measured by sensor 18, and the total concentration of fluoride in products

Combustion device 19 is provided in fluorinated water; a meter 20 is used to record the degree of defluorization of the feed phosphate melt (fluorine concentration in the final product).

The proposed method is carried out as follows.

When implementing this method, use the following dependencies. When increasing the concentration of fluorine in the test solution 3 times, the solution in the measuring cell should be diluted 3 times more with the buffer. Let us show, in mathematical form, the transition to a linear dependence of the measured value (consumption of a buffer solution) on the concentration of fluorine in the test solution.

Let Cd - be a given constant concentration of fluorine in the measuring cell, achieved by changing the flow rate of the buffer solution when the concentration of fluorine in the analyzed solution changes; Gff is the constant flow rate of the analyte through the analytical cell; C is the concentration of fluorine in the solution being analyzed; ) the consumption of the buffer solution (automatically changing the value, then

G1, p

Cd p - - ::; - (constant value), o + Buor

from here

С с „+ с

k for

With

evopc; - processes

under consideration

and can be excluded.

WITH.

A straight line equation is obtained in coordinates Gpyj ,,, C.

In this method, the registration of the emf with a potentiometer is replaced by 45 recording the concentration of fluorine from a buffer solution flow meter with a uniform scale scaled to the concentration of fluorine in the analyzed solution. Thus, the concentration of fluorine is determined by the automatically varying flow rate of the buffer solution when the concentration of fluorine in the concentration is constant. control cell (constant emf).

55 When changing the concentration of fluorine in the analyzed solution entering the cell with sensors (electrodes), the flow rate of the buffer solution changes so that the return cell speed (and a)

cheat and the concentration of the solution in the cell) to the original value.

The test medium (products of combustion) and the buffer solution are fed into the flow measuring cell. The delivery rate of the test medium is set at a constant level, controlling its flow with a rotometer 10 and a compensation with its controller 11, which is kofate C | determined by you reading device 18 (C,,

Example. The degree of defluorization of feed phosphates is determined as follows.

To determine the concentration of fluorine (F) in the combustion products of 1 l / min of flue gases with an F content of 50 mg / m, it is bubbled through the cuvette.

mu set the task stabiliziro- Oh which is embedded in fluoroselective

Fatah C | determined by subtractor 18 (C,,).

Example. The degree of defluorization of feed phosphates is determined as follows.

To determine the fluorine concentration (F) in the combustion products of 1 l / min, flue gases with an F content of 50 mg / m are bubbled through a cuvette.

The value of the flow rate of the combustion products at the level of the maximum sensitivity of the electrodes 5 using the control valve 12, is technically difficult to prepare a solution in the flow measuring cell 4 with an optimal concentration of controlled fluorine for measuring. If the concentration of fluorine in the combustion products changes, the flow rate of the buffer solution is changed using an automatic tracking system (5–9) so that the concentration of fluoride ions in cell 4 is at the level that is optimal for measurement. The EMF signal of the pair of electrodes 5 is fed to the measuring device 7, the output of which is connected to the regulator 8 ,. control valve 9. The latter sets the flow

/five

20

25

electrode and reference electrode.-0.23 L / min of buffer solution (pH 5.8-6.0) is supplied to the branch. The degree of whelk fluoride 0.95. The concentration of ft ion in the cuvette is maintained at y not 1 CHO g-ion / l. When changing the concentration in the gas to 500 mg / m to maintain the concentration of fluorine and E-pair at a constant level, the flow rate of the buffer solution is 2.5 l / m. Prior to this example

CK 200 GS,

Where G is the flow rate of the buffer solution l / min;

fluorine concentration in gas mg / m.

x

The measurement error of the proposed method due to nest

buffer solution at this value, the absorption coefficient bilnosti.

the fluorine concentration in the cuvette of the lysing substance in the solution (fto-35 exceeds + 1.5%) varies depending on the flow rate by + 0.5% and the inaccuracy of the automatic stabilization system {-t1.0%).

so that the concentration of the monitored ion in the measuring cell 4 is maintained at a predetermined level.

The desired value of the anzra) sous concentration is determined by the flow rate of the buffer solution measured by the rotameter 14, since the indicated flow rate is directly proportional to the output signal of the regulator 8. The flow signal of the buffer solution from the rotameter 14 is fed to the functional converter 15, which realizes the function the consumption of the analyzed medium).

de C

Su.K

 To GC Gp,

analyte concentration;

linear dependence coefficient; buffer flow rate.

The concentration of fluoride C in fluorinated water is determined in a similar way.

The total value of the concentration of C fluoride in water and combustion products is determined by the adder 17 (+ С „

A l 2

and the concentration of fluorine in feed phosphorus 50 50),

five

0

five

The electrode and the reference electrode. Into the cuvette, 0.23 L / min of the buffer solution (pH 5.8-6.0) is supplied. Fluorine absorption rate is 0.95. The concentration of fluoride ion in the cuvette is maintained at 1 CHO g-ion / l. When changing the concentration in the gas to 500 mg / m to maintain the concentration of fluorine and EMF of the pair at a constant level, the flow rate of the buffer solution is 2.5 L / min. Prior to this example

CK 200 GS,

Where G is the flow rate of the buffer solution, l / min; :

fluorine concentration in gas. mg / m

x

The measurement error of the proposed method due to nest 5

For determination of fluorine concentration. the ion in the liquid cooling the feed phosphate melt, 0.01 l / min of water, containing 20 mg / l of fluorine ion, is mixed with 1 l / min of the buffer solution in the measuring cell, in which: a fluoroselective electrode is embedded

and a reference electrode (chlorine-silver), 45 The concentration of fluoride ions in the cell is maintained at a level of 1X) ilOg-ion / l. When the concentration of fluoride ions in water is reduced to 5 mg / l to maintain a constant 50 fluoride ion concentration in the measuring cell, a buffer solution flow of 0.25 l / min is required. When increasing the concentration of fluoride ions in water to 100 mg / l, to maintain a constant concentration of fluoride ion in the measuring cell, a consumption of a buffer solution of 5 l / min is required. For this example

Cv, 20 GS,

Where

Gg - consumption of buffer solution,

l / min;

С - concentration of fluoride ion in water, mg / l.

The relative measurement error for this method is 1.0%.

Appreciating soo and

C using functional converters 15 and 16, C 17 Cy is determined on adder 17, Cy is + C, and block 18 is used to determine the difference between fluorine concentration in initial phosphate C and total fluorine concentration in gases and in the cooling melt C, which determines the concentration of fluoride in the final product (melt) of feed phosphate

 F. The proposed method of determining

The degree of defluorization of feed phosphates allows continuous automatic control of the analyte, which increases the control accuracy by 4 times.

Claims (2)

1. The method of controlling the degree of defluorization of feed phosphates, semi obtained by treating phosphorites with a high-temperature flow of fuel combustion products, followed by cooling the resulting melt with water, settling the mixture in the granite tower and measuring the fluorine concentration in the product, characterized in that, to ensure continuity of the control, the fluorine concentration is measured in phosphorites, combustion products at the output of the energy technology apparatus and fluorinated water at the outlet of the granule and determine the concentration of fluoride in the final product by the difference between fluorine concentration in phosphorites and total concentration, fluorine in the combustion products and fluorinated water. 2. The method according to claim 1, characterized in that, in order to increase the control accuracy, stabilize the fluorine concentration values in the measuring cells by varying the supply of the buffer solution and determine the fluorine concentration in the combustion products and fluorinated water according to the consumption of the buffer solution in measuring cells.