SU915963A1 - Method of automatical control of grinding cycle - Google Patents

Description

The invention relates to the automatic control of the process of enrichment of minerals and can be used in the processing of ores with varying physico-mechanical and chemical-mineralogical properties, as well as in conditions of drift of the statistical characteristics of technological units, caused by their wear.

There is a method of automatic control of a mill operating in a closed loop with a classifier, including stabilization of the classifier’s discharge density by changing the filling of the mill with raw material and water [].

The disadvantage of this method is that, since the optimal mode of the process of grinding raw materials associated with finding a working point in the extremum of statistical characteristics, then this mode will always be accompanied by self-oscillations in

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a closed grinding cycle (the optimal conditions for the process of grinding raw materials in closed grinding cycles always correspond to the limit of stable modes of the grinding process).

The closest to the proposed method is the automatic control of the grinding cycle in a mill operating in a closed cycle with a classifier, including measuring the content of the selected size class of the solid pulp fraction in the output product and the change in water flow into the classifier [2].

However, the grinding and classifying equipment at the processing plant most of the time work in unsteady transient conditions, the parameters of which are determined by the cycle transfer coefficient for the selected size class, i.e. gain in the transfer function of the object

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management. Changes in the quality of the processed raw materials and the state of the process equipment lead to fluctuations in this parameter, which entails a deterioration in the quantitative and qualitative characteristics of transients in a closed control system and, as a consequence, a decrease in the yield of the selected “finished” size class in the output product of the cycle.

The purpose of the invention is to improve the quality of management.

. This goal is achieved by

(that in the method of automatic control of the grinding cycle in a mill operating in a closed cycle with a classifier, including measuring the content of the selected size class of the solid pulp fraction in the output product and changing the water flow into the classifier, the current deviation of the content of the selected class in the output the current deviation modulus is determined by the product from the specified value; the moment when the derivative of the modulus of the current deviation reaches the zero value after the The beginning of the transition process, after which the current deviation modulus and the maximum modulus value of the derivative of the current deviation are measured, and the ratio of the measured values is calculated, and the change in water flow to the classifier is performed depending on the product of the ratio of the measured values by the current deviation value.

The drawing shows a block diagram of the automatic control system of the grinding cycle that implements the proposed method.

The control object is a mill 1, operating in a closed loop with a classifier 2.

The automatic control system contains a device for controlling the granulometric composition of the solid in the pulp 3, for example, of ultrasonic type, connected to the first input of the comparison element 4, to the second input of which the setting device 5 is connected, and to the output - the first input of the multiplication unit 6 and the input of the first module 7 of the module definition , the output of which through the first filter 8 is connected with the inputs of the limiter 9 and the differentiator 10, connected by its output with

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the input of the second module 11 for determining the module and the first input of the logic unit 12, the output of which is connected via the first input unit of the storage and data retrieval unit through the unit 13 for generating the time delay, the second input of the logic unit 12 and the first input of the amplitude detector 15, the second input of which is connected to the output of the second unit 11 of the definition of the module, and the output is connected to the first input of the computing device 16, the second input of which is via a scaling unit. 17 associated with vy15 stroke limiter 9, and an output connected to a second input of the storage device and retrieving information, whose output is connected to the third input of the calculation unit 16 and the second WMOs _m house multiplication unit 6 connected to its output to the input driver 18 of the control action, as which can be used standard proportional-integra ₂₅ ratival-differential (PID) controller, the output of which through the actuator 19 is connected with an adjustable valve 20.

The automatic control system for the grinding cycle works as follows.

The processed ore, crushed in the mill 1, is divided in the classifying apparatus 2 into a large fraction returned for regrinding in the mill 1 and fine, which enters the enrichment unit as part of the output product from the discharge of the classifying apparatus 2.

The task of the grinding cycle is the complete disclosure of the grains of the useful component without over-grinding.

The degree of grinding or the value of the content of the selected controlled particle size of the solid pulp fraction at the discharge of classifier 2 is determined by the impregnation nature of the useful component and is set by the setting device 5 The current content X value of the selected grain size of the crushed material in the output product of the cycle from the pulp control 3 Element 4 Comparison ⁵⁵ with the setting signal of the generator 5 X3. In the first block 7 of the module definition and the first filter 8, the filtered signal of the error module is allocated

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Ιζ, Ι, representing the difference between the current X and the specified values of the content ^^ of the selected size class of the solid fraction in the output product of the cycle. _five

Differentiator 10 estimates the derivative £ of the error signal module 1Б1, and the second module 11 of the module definition, together with the amplitude detector 15, extracts the maximum value of the module of the derivative of the error signal, y.

Value | from the first filter 8, multiplied by the constant coefficient K in the scaling unit 17, and 15 also the value of y is fed to the computing device 16, which implements the calculation of the correction factor CL:

where <Λ _γ and <А _П are the current and previous values of the correction factor.

| To increase the reliability of the automatic control system 25, limiter 9 sets the range of variation of the magnitude of the error signal | E (i.e., the maximum value of 1 £ | that can be used to calculate <L.

Logic block 12, which is connected dva.posledovatelno trigger to achieve a zero knowledge derivative module ₃₅ cheniya error signal I (provided in front of this exit outside the deadband logic unit 12) starts forming unit 13 extracts time which is selected through kont- _{The 40th} time interval forms a pulse according to which in the device 14 for storing and retrieving information, a comparison is made of the recorded previous and current values of the correction factor. The same signal resets the old value of y in the amplitude detector 15 and returns the logical block 12 to the initial state. ₅₀

If the previous value of & does not differ from the current value of SL,., And this is possible if the parameters of the control object have not changed

(i.e., the ratio is), then the previously recorded and stored ^ value of cP is stored, is present at the output of the storage and sampling device 14, and returns to the computing device 16. The error signal £ is multiplied by this in block 6 of multiplication. . \

The exclusion of £ out of the limits of the insensitivity zone of logic unit 12 means the occurrence of a significant transient mode as a reaction of a closed control system to a disturbance, which practically means exceeding | the level of operation of the logic unit 12.

Measurement of the magnitude of the error signal module! £ | after a certain period of time after the derivative ί reaches the zero value (provided that the value перед is outside the sensitivity zone), it corresponds to measuring the value 1 измер some time after the error reaches its maximum value for the current transient mode. In the case of a damped transient, this allows us to estimate the damping rate and, consequently, the speed (of the control object. '

Decreasing the transmission coefficient of an object along the selected control channel decreases its speed 1 € 1

Wie, the ratio increases - ~ -,

and consequently, the correction factor is formed which is formed in the computing device 16.

Conversely, with an increase in the transmission coefficient of an object, its speed increases, and the ratio decreases.

- and, as a result, the correction factor o * 'decreases.

In the case of a divergent transition process at the output of the storage and sampling unit 14, the minimum value of the correction factor cL is established, which makes it possible to increase the degree of stability of the closed-loop control system.

In multiplication unit 6, the current value of the error signal is multiplied by the correction factor oA, and the product of these quantities is fed to the start of the control driver 18 (PID controller), which generates a control action on the actuator 19 according to the law, the parameters of which are determined taking into account the corrected signal value errors £.

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The actuator 19, by changing the position of the adjustable valve 20, controls the flow of water into the classifying apparatus 2 and thereby controls the particle size distribution of the output product of the cycle.

Thus, the automatic control system of the grinding cycle counteracts the effect of changes in the parameters of the control object, i.e. the quality ^{of the} processed raw materials and the state of the process equipment by adjusting the channel’s own transmission coefficient: water consumption into the classifying apparatus 1 2 - content of the selected size class of the crushed material.

The method of automatic control of the grinding cycle can improve the performance of the cycle for ² selected class size 0.20,3%.

This contributes to an increase in the yield of the concentrate of a given quality with an overall decrease in the consumption of raw materials ² per ton of concentrate.

Claims (1)

Claim 3 The method of automatic control of the grinding cycle in a mill operating in a closed cycle with a classifying apparatus, including measuring the content of the selected class size of the solid pulp fraction in the output product and changing the water flow to the classifying apparatus, 5 characterized in that, in order to improve the quality of management, the current deviation of the content of the selected class in the output product from the specified value is additionally measured ⁰ values, determine the module of the current deviation, fix the moment of reaching the derivative of the module of the current deviation of zero value after the beginning of the transition process, after ⁵ which measures the module of the current deviation and the maximum value of the module of the derivative of the current deviation and calculates the ratio of measured values, and the change in water flow to the classifying apparatus is carried out depending on the value of the product of the ratio of measured values by the value of the current deviation.