SU1659501A1 - Method for automatically controlling fluidized bed firing of nickel concentrate with recycles - Google Patents

Abstract

This invention relates to non-ferrous metallurgy, in particular to the production of nickel oxide in KS furnaces. The purpose of the invention is to reduce the loss of metals with dust removal and oxygen saving. To this end, the content of sulfur in the concentrate is additionally measured, the deviation from the given value is determined by the formula A Cs Cgad-Csi, where D Cs is the deviation of the sulfur content in the concentrate from the set value; C | hell is the specified value of the sulfur content in the concentrate; Csi is the measured value of the sulfur content in the concentrate, calculate the derivative of the sulfur content in the concentrate using the formula dCs / dT Csi - Cs l - l / I - r (i - 1), where dCs / dr is the derivative of the sulfur content in the concentrate: CsA- L is the previous value of the sulfur content in the concentrate; b is the instant of measurement of the current sulfur content in the concentrate; T (i) is the time of measurement of the previous sulfur content in the concentrate; the amount of control correction is determined — the change in oxygen consumption depending on the weighted sum of deviations of the sulfur content in the concentrate from the set value and the derivative of the sulfur content in the concentrate using the formula AQ.02 Kn-ACs + Kg- (dCs / dr), where AQoz is the required correction of the magnitude of the control action of the oxygen consumption; Kn and Kg - tuning factors; (Kp 0.8-1-1,1; Kg 0.5-0.7), then the control action on the oxygen consumption is changed by the value of the calculated correction, and the air consumption is adjusted in inverse proportion to the change in the oxygen consumption. 2 hp f-ly, 1 ill. Ov

Description

The invention relates to non-ferrous metallurgy and can be used in the automatic control of a fluidized bed roasting process.

The purpose of the invention is to reduce metal losses with dust removal and to save oxygen.

The drawing shows the setup diagram that implements the proposed method of automatic control of the firing process

nickel concentrate with fluidized bed turnover.

The installation includes a fluidized bed furnace, a screw conveyor, a rotation loading line, a revolution weight meter and an analyzer of sulfur content in the concentrate.

A task for the flow rate blowing is entered into the control computing device 1, the analyzer 2 is used to determine the sulfur content in the concentrate, and after weighing it on the weight measuring device 3, the load rate is

The control computing device 1 calculates the task for controller 4 for oxygen consumption in zone 5 of the load and controller 6 for the task for oxygen consumption in zone 7 of the hearth adjacent to zone 5 Downloads, using the formula:

Qo2 Kn - (20 - CsO - Kg (Csi - Cs (,,)) +

+ Cob-bob at C 20%;

Q $ 2 0.3;

Q & 2 0.7,

 Qo2 task for the oxygen consumption in the Furnace KS, thou.me / h;

Csi - current sulfur content in concentrate,%;

Kp - proportionality coefficient (0.8-1.1);

Q $ 2 task for oxygen consumption in the Zone 5 loads, thousand m3 / h;

Q & 2. the task of oxygen consumption in Zone 7 of the hearth, adjacent to the loading zone - Ki, thousand m / h;

Cs (t is sulfur content at the previous step,%;

Kg is the proportionality coefficient before the derivative of sulfur content (0.5-0.7);

Sob - the weight of the load turns, t;

Kob - proportionality factor before the consumption of turns (0.1-0.3).

Depending on the size of the task for oxygen consumption, device 1 determines the task for controller 8 for air flow to Zone 5 and controller 9 for task for air flow into zone 7 by the formulas:

izozd: ovoed

here -ud, Ov8zd - QO.

where $ 0 ozd is the task for air flow in the zone 5, thousand m3 / h;

Ozd - the total task for the flow rate to blow into the zone 5, thousand m3 / h;

Ovozd - task for air flow to Ion 7, thou. M / h;

Ov8zd - the total task for the flow rate to blow into the zone 7, thousand m3 / h.

PRI me R 1 (by a known method). Process control without adjusting the oxygen consumption for the content and rate of change (derivative) of the sulfur content in the concentrate.

The average furnace capacity is 13.6 t / h.

Consumption blow, thousand m / h; air 19.0; oxygen 3,5, the average coefficient of excess

the total oxygen content in the blast is 1.87.

The temperature in the bed varies between 1040-1190 ° C.

The granulometric composition of the resulting cinder is in the range,%: Fraction +1.2 mm 8-20 Fraction -1.2 + 0.5 mm 20-70 Fraction-0.2 mm 0-30% Material balance determined

5, the average dust removal rate is 38% of the concentrate load. Taking into account the existing dependencies of losses on dust removal, nickel losses in this firing mode are determined at a rate of 1.7% of the load.

The content of sulfur dioxide in the gases after the KS furnace is in the range of 5-15%.

The load of revolutions, the consumption of oxygen and air do not change over time.

5 At the beginning of the control period, the sulfur content in the concentrate is 19.8%.

The temperature in the layer is 1192 ° C. After 6 hours of work, the sulfur content in the concentrate

0 decreased to 17.2%. As a consequence, the temperature began to fall despite the measures taken to increase the load. This is due to the imbalance of heat at a given temperature level due to

5 of a large amount of ballast load in the form of concentrate dust and physically associated moisture. Approximately during 17 h the temperature level is lower than the required one. During this period, the process went with increased

0 by dust removal, received a cinder with an increased amount of small fraction. The firing mode was normalized only with a decrease in the supply of dust to the thickeners and an increase in the sulfur content in the concentrate to 19%.

5 The dust accumulated in dust-removing systems for the period of temperature failure of the firing mode was to be processed outside the control period when set in the task for the increased concentration mode.

0 oxygen in the blast.

The specific consumption of oxygen for a period of 250 m per 1 ton of concentrate. Usually (as in this case), with manual control, an excessively high oxygen excess is maintained because of the fear of overloading the furnace.

On the whole, the period is characterized by thermal instability, sharp fluctuations in the output parameters of the process, and unsatisfactory technical and economic indicators.

PRI mme R 2. Automatic process control with adjustment of oxygen consumption in terms of content and rate of change (derivative) of sulfur content in concentrate.

The equations for calculating the assignment and automatic control of the flow of air and oxygen are of the form:

Qo2 0.2Go6 + 0.9 (20 - Csi) - 0.6

dCs dr

where Qoa is the task for oxygen consumption, thousand m3 / h;

Col - flow rate, t / h;

Csi - current sulfur content in concentrate,%;

dCs

 rate of change (produces

concentration of the medium in the concentrate. % / h;

Q $ 2 0.3;

Q & 2 0.7,

where Q & 2 is the task of oxygen consumption in the prechamber, thousand m3 / h;

Q & 2 task for oxygen consumption per unit, thousand m3 / h.

Jozd

here

Ovazv8z Q & 2.

where - the task of air flow in the prechamber, thousand m3 / h;

0 | oed - task for the flow rate to blow into the prechamber, thousand m3 / h;

Ovozd - task for air flow to the hearth, thousand m3 / h;

Ovoz - the task of the flow to blow on the hearth, thousand m3 / h.

Periodically (once per hour) a sample of nickel concentrate is taken, sent by pneumomail to an X-ray spectrometer for analyzing the sulfur content, the results of the analysis are obtained by teletype and entered into a computer. The analysis delay is 40 minutes to 1 hour.

During the experiment, the average capacity of the KS furnace for concentrate processing is 13.8 t / h. The load is stable.

The flow rate of the blow is th. M3 / h: air 17.0-18.0; oxygen 1.8-3.5, the average coefficient of excess blowing (according to the total oxygen content in the blast) is 1.3.

The temperature in the bed varies between 1100-11606C.

The granulometric composition of the cinder obtained is within,%: Fraction +1.2 mm 8-12 Fraction -1.2 + 0.5 mm 40-60

Fractions -0.2 mm 2-5

According to the material balance, the average dust extraction for a period of 27% of the concentrate load is determined. Taking into account the existing dependencies of metal losses from dust removal, the loss of nickel alone in this mode is 1.1%. The content of sulfur dioxide in the gases after the furnace is in the range of 10-17%.

Sulfur content during the observation period

in the concentrate it changed in the range of 16.3–19.5%. The temperature in the layer was maintained at the optimum level during the entire control period due to the almost continuous correspondence of the arrival and heat consumption in the CS furnace at any concentrations of sulfur in the concentrate. This was achieved by the fact that when the sulfur content in the concentrate was reduced, an adjustment for the quality of oxygen blowing was automatically introduced. Than

the greater the decrease in the sulfur content in the concentrate, the greater the concentration of oxygen maintained in the blast and vice versa. Moreover, the oxygen concentration in the blast was changed by a corresponding adjustment of the oxygen supply to the blast and the reverse volume of air supply. In the period of approaching the minimum sulfur content in the concentrate, the total oxygen concentration in the blast reached

35%. The relative stabilization of the temperature in the bed ensured for the control period the obtaining of an calcine with a minimum content of the dusty fraction, a decrease in dust removal and metal losses. More

quality stable was also gas for sulfur utilization. Only briefly the oxygen consumption amounted to 3.5 thousand m3 / h, mostly for the period it was maintained at the level of 2-2.5 thousand m3 / h. Specific consumption

oxygen was 180 m3 per 1 ton of processed concentrate. The excess oxygen ratio is maintained at the minimum required level, ensuring the thermal stability of the process and the quality

stub

Claims (3)

Claim 1. A method for automatically controlling the process of roasting a nickel concentrate with fluidized-bed turns on an oxygen-enriched blast with a cinder coarsening, including controlled supply of air and oxygen to the furnace, loading of concentrate and turns, distribution of oxygen between the loading zone and The adjacent working area, depending on the magnitude of the load of revolutions, monitoring the process parameters, characterized in that, in order to reduce metal losses with dust extraction and to save oxygen, the content of sulfur in the concentrate is measured, the deviation from the predetermined value is determined by the formula ACs- C§ad-C8 |, where A Cs is the deviation of the sulfur content in the concentrate from the specified value; C | ( RD set point of content sulfur in concentrate; Csi is the measured value of the content of Sulfur in concentrate, Calculate the derivative of the sulfur content in the concentrate using the formula (i-i) dr ri - r (i -1) where dCs / dr is the derivative of the sulfur content of ft concentrate; Cs (1 -1) is the previous value of the sulfur content in the concentrate; 0 five 0 five 0 ri is the instant of measurement of the current sulfur content in the concentrate; G (s) is the instant of measurement of the previous sulfur content in the concentrate, determine the amount of control correction - the change in oxygen consumption depending on the weighted sum of the deviation values of the sulfur content in the concentrate from the specified value and the derivative of the sulfur content in the concentrate using the formula A Qo2 Kn -ACs + Kg (dCs / dr), where AQoa is the required correction of the magnitude of the control action of the oxygen consumption; The kn and kg are the tuning coefficients, then the control action on the oxygen consumption is changed by the amount of the calculated correction, and the air consumption is adjusted in inverse proportion to the change in the oxygen consumption. 2. A method according to claim 1, characterized in that the oxygen consumption is adjusted when the sulfur content in the concentrate is less than 20%. 3. Method 1, characterized in that the air flow rate is adjusted for the magnitude of the change in the oxygen flow rate. Turnovers L Concentrate Lie down the cop