RU2428256C1 - Method of controlling wet self-grinding of slime in mill - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: proposed method comprises measuring and adjusting charge of materials to be crushed and measuring water and plasticiser flow rate. To optimise controlled parameters, reduce power losses and stabilise slime quality, slime viscosity and moisture content at mill outlet are measured. Besides, chemical composition of crushed materials at mill inlet and outlet is measured. Additionally, mill yield and slime density at mill outlet are measured. Water and plasticiser feed are minimised according to slime viscosity and moisture content. Feed of materials to be crushed is adjusted according to measured mill efficiency and slime feed. Additionally, ratio and feed of materials are adjusted according to measured chemical composition and slime chemical composition at mill outlet. ^ EFFECT: reduced power consumption, higher quality of crushing. ^ 3 dwg

Description

The essence of the invention. The invention relates to the production of building materials, namely to a wet method for the production of Portland cement clinker at the stage of preparation of the raw mix. The aim of the invention is to reduce energy consumption for sludge and clinker cement production, increasing the productivity of technological equipment, as well as improving and stabilizing the quality of coarsely ground sludge.

The essence of the invention is to continuously control the viscosity and humidity of coarsely ground sludge at the outlet of the Hydrofol wet self-grinding mill by changing the water supply and plasticizer LST at the inlet of the mill, while the chemical composition of coarsely ground sludge is constantly adjusted by changing the ratio of the supply of chalk and clay to the Hydrofol mill ".

Correction of the supply of chalk and clay is carried out as a result of continuous measurement and comparison of the estimated physicochemical composition of chalk and clay fed to the Hydrofol mill and the calculated chemical composition of coarsely ground sludge at the outlet of the Hydrofol mill. At the same time, the supply of chalk and clay is adjusted to set the properties of the raw mix, for example, its titer, as well as comparing the calculated composition of the raw mix at the inlet of Hydrofol and the measured chemical composition of the sludge at the outlet of the Hydrofol mill. The proposed method also continuously measures the viscosity, humidity and density of the sludge at the outlet of the mill, as well as the performance of the mill unit, and based on continuous monitoring and control of viscosity, density and humidity of the sludge at the outlet of the mill, an increase in the performance of the Hydrofol mill is achieved.

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Class (s) of patent: В02С 25/00

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Authors: Besedin Pavel Vasilievich (RU); Filatova Elena Petrovna (RU); Novichenko Andrey Valerievich (RU); Panova Olga Alexandrovna (RU).

Patentee (RU): Authors

Description of the invention. The invention relates to automation of the process of wet self-grinding of materials in mill units, and in particular in Hydrofol mills. It can be used in the construction materials industry in the production of cement, in the metallurgical, chemical and other industries related to wet grinding processes.

A known method of controlling the process of wet self-grinding of materials in a mill unit [1], including the amount of load and water consumption to optimize a controlled parameter, while the specific optimization parameter is determined by the specific consumption of electric energy for grinding by controlling the flow of water depending on the difference in temperature of the pulp at the outlet and water at the inlet and the load of the mill unit. However, this method does not provide high quality control of the grinding process, for example, due to temperature fluctuations in winter and summer, during the day - day and night, since the materials to be ground are usually located in open areas, and the residence time of the ground materials in mills wet self-grinding is small.

Closest to the technical nature of the invention is another way to control the process of wet self-grinding of materials in a mill unit [2], including stabilization of the sound parameter of the mill and the size of the classifier drain, measuring the flow of ore and water to the mill, water flow to the classifier, calculating the ratio of liquid to solid in the discharge classifier and change in the flow of water to the mill. And in order to increase the efficiency of the grinding process, the additionally measured amount of ore flow into the mill is multiplied by the calculated ratio of liquid to solid in the plum classifier, and then the measured value of the water flow into the classifier is subtracted from the product value, and the change in water flow to the mill is maintained equal to the calculated difference [2 ].

The disadvantage of this method is that the process of controlling the loading of the mill is carried out according to the sound parameter, while maintaining the noise of the mill at a given level. However, it is known that when parallel grinding mills operate, the sound parameter is distorted, in addition, the noise level in the mill depends on the physicochemical properties of the milled materials, for example, moisture, hardness, density and others, therefore, the sound signal does not provide high quality control grinding process. In addition, the flow of water to the mill is changed by calculation, in fact, the ratio of liquid to solid, i.e. regulate the density of the pulp, consisting of water and ore. Direct measurement of moisture and pulp density allows for better control of the process of grinding materials in wet mills.

The aim of the invention is to reduce energy consumption for the production of sludge and clinker cement production, increasing the productivity of technological equipment, as well as improving and stabilizing the quality of coarsely ground sludge. The goal is achieved by optimizing the controlled parameters, stabilizing the quality of the resulting sludge, as well as using the proposed method for controlling the process of wet self-grinding of coarsely ground sludge in the Hydrofol mill.

It is known that when a plasticizing reagent is introduced into the sludge, its viscosity decreases, its spreadability and fluidity increase, however, different reagents have different plasticizing properties, and different clays and chalks have different ability to absorb water and react differently to plasticizers. In this regard, it is necessary to regulate both the water supply and the supply of plasticizers.

However, the introduction of a plasticizer allows not only to reduce the viscosity of the sludge, but also to reduce its moisture content, to increase its flowability and fluidity. This improves the transporting properties of the sludge through pipelines, which leads to a reduction in energy consumption by reducing the load on the electric motors of the pumps pumping sludge.

It is also known that a decrease in sludge moisture leads to a reduction in energy consumption for clinker firing, for example, a 1% reduction in sludge moisture reduces fuel consumption for clinker firing to 4 kg of standard fuel per ton of clinker.

Therefore, to reduce energy consumption, it becomes necessary to regulate the water supply at the inlet to Hydrofol, depending on changes in the viscosity and humidity of the sludge at the outlet of Hydrofol.

It is also known that the feedstock mined in the quarry - chalk and clay - changes its physicochemical properties. For example, the content of CaCO ₃ in natural chalk can vary from 90% to 99%, and in limestone and marls the content of CaCO ₃ can also change in a wider range. The physicochemical composition of clays also changes. In this regard, to stabilize the chemical composition of the obtained coarsely ground sludge, it is necessary to measure the chemical composition of chalk and clay, as well as adjust the weight ratio of the feed of these raw materials to Hydrofol.

Thus, in order to obtain a high and stable quality of coarsely ground sludge, i.e. to stabilize its chemical composition, it is necessary to continuously regulate the supply of chalk and clay in accordance with the specified and calculated properties at the entrance to the Hydrofol. On the other hand, to reduce the moisture content of the sludge, increase its spreadability, and reduce the viscosity, it is necessary to continuously monitor the viscosity and humidity of the sludge, as well as continuously control the process of supplying water and plasticizer.

The implementation of the set goals and objectives to reduce sludge moisture, reduce energy consumption for clinker burning and reduce electric energy for pumping sludge, as well as stabilize the quality of the resulting sludge, can be carried out using the control system for the preparation of coarsely ground sludge, shown in the diagram of Fig. 1.

The control scheme for the preparation of coarsely ground sludge (figure 1) includes the following equipment: "Hydrofol" - 1; receiving hopper and feeder for feeding chalk - 2; receiving hopper and clay feeder - 3; water supply pump - 4; water flow meter - 5; plasticizer feed pump LST - 6; plasticizer supply meter LST - 7; Hydrofol sludge discharge hopper - 8; moisture meter w sludge - 9; sludge viscosity meter - 10; sludge density meter - 11; pump for transferring sludge to a vertical pool - 12; sludge flow meter at the exit of "Hydrofol" - 13; a spectrometer for measuring the chemical composition of coarsely ground sludge at the exit of Hydrofol - 14; a spectrometer for measuring the chemical composition of chalk and clay at the entrance to the Hydrofol - 15; weight dispenser for chalk supply D1 - 16a; chalk supply regulator R _m - 16; weight dispenser for clay supply D2 - 17a; clay feed regulator R _g - 17; water supply regulator P _in - 18; plasticizer supply regulator R _pl - 19; Hydrofol loading hopper - 20; asynchronous motor tape dispenser chalk AD1 - 21; clay induction motor of clay dispenser AD2 - 22; AD3 - 23 asynchronous motor for water supply pump; asynchronous motor of the plasticizer feed pump LST AD4 - 24; chalk feed dispenser - 25; clay feed dispenser - 26; the regulator regulator R _m supply of chalk in "Hydrofol" - 27; the regulator regulator R _g clay feed in "Hydrofol" - 28; the regulator of a regulator of a consumption of water P _in - 29; plasticizer consumption regulator adjuster LST R _pl - 30; vertical pool for the preparation and accumulation of coarsely ground sludge - 31; dump truck for feeding chalk to Hydrofol from the quarry - 32; a dump truck for feeding clay to Hydrofol from a quarry - 33.

The method of controlling the wet self-grinding process of coarsely ground sludge in the Hydrofol mill is carried out in the following sequence: chalk and clay from the quarry are fed by dump trucks 32 and 33 to the receiving bins 2 and 3; chalk and clay are fed from receiving hoppers 2 and 3 using tape dispensers 25 and 26 into the feed hopper 20 of Hydrofol, while chalk and clay samples are preliminarily taken, which are analyzed by chemical composition on spectrometer 15, and the chalk loading is monitored and clay weight dispensers 16A and 17A. In addition, with the help of pumps 4 and 6, water and LST plasticizer are fed into the Hydrofol loading hopper, while the flow of water and LST is controlled by flow meters 5 and 7.

The process of regulating the supply of chalk and clay is carried out using asynchronous motors 21 and 22, to which a control signal from the regulators 16 and 17; in turn, controllers 16 and 17 for supplying chalk and clay from the calculation unit (Fig. 2) of the chemical composition of the mixture are supplied with control signals 42 and 43 of the calculated value of the charge of chalk and clay, which correct the task of loading chalk 27 and the task of loading clay 28.

The regulation of water supply and plasticizer LST is carried out according to the scheme shown in figure 3. The regulation process is carried out in the following sequence: the water flow rate controller 29 and the flow rate of the plasticizer LST 19 are fed with the water flow rate 29 and the flow rate of the LST 30, and corrective signals 44 and 45, which characterize the calculated water flow rate and LST. At the same time, at the exit from Hydrofol, the self-grinding process is controlled by moisture w of the sludge with a moisture meter 9, viscosity η of the sludge with a viscometer 10 and density of the sludge ρ with a densitometer 11. In addition, the performance of the Hydrofol mill with a flow meter 13 is additionally controlled, and the chemical composition of coarsely ground sludge is determined by a spectrometer fourteen.

The method for regulating the chemical composition of the sludge, its viscosity and humidity of coarsely ground sludge includes two control loops. The first control loop provides for regulation of the chemical composition of the sludge at the inlet to the Hydrofol mill and at the outlet of the finished coarse sludge from the mill. The second circuit provides for the regulation of viscosity η and humidity w of coarsely ground sludge at the outlet of the Hydrofol mill.

The regulation of the chemical composition of coarsely ground sludge in the primary circuit (FIG. 2) is carried out as follows: from the selected samples of chalk and clay supplied to Hydrofol, the chemical composition of chalk and clay is determined on spectrometer 15. The chemical analysis data of the selected samples are supplied to the calculation unit 34 of the chemical composition of coarsely ground sludge. In addition, data obtained from sensors D1 and D2, the measured amount of chalk and clay fed into the Hydrofol bunker are entered into the block for calculating the chemical composition of coarsely ground sludge. Moreover, in the block calculation 34 is determined by the quantitative weight ratio of chalk and clay. According to the calculation results, tasks 42 and 43 are given to the flow control registers of chalk R _m 16 and clay R _g 17. The calculation value 34 of the chemical composition of the raw material mixture, determined on the spectrometer 15 at the entrance to Hydrofol, additionally provides the actual value of the chemical composition of coarsely ground sludge obtained according to the results of measurements on a spectrometer of 14 selected sludge samples at the exit from Hydrofol.

Thus, the scheme of calculating the chemical composition of coarsely ground sludge and adjusting the supply of chalk and clay to the Hydrofol mill presented in FIG. 2 allows us to stabilize the given chemical composition of coarsely ground sludge at the outlet of Hydrofol. Fluctuations in the chemical composition of chalk and clay at the entrance to Hydrofol can occur due to changes in the chemical composition of natural rocks of chalk and clay, which are mined in the quarry and fed to Hydrofol.

The regulation of viscosity η and moisture w of the sludge is carried out according to the scheme shown in Fig.3. Figure 1 shows that at the exit from the hopper of the mill "Hydrofol" installed sensors 9 and 10 measuring the moisture and viscosity of the sludge. The measured values of humidity 38 and viscosity 39 are supplied to blocks 36 and 37 of calculating the consumption of plasticizer LST and water consumption.

In block 36 calculation LST (figure 3) compares the set value 40 of the viscosity of the sludge with the measured value 39 of the viscosity of the coarsely ground sludge at the exit of "Hydrofol". If the measured viscosity 39 of the sludge is higher than the preset value 40, task 45 issued to the LST flow controller 19 by the LST flow calculation unit 36 increases the consumption of LST, and if the measured viscosity 39 of the sludge is lower than the set value, task 45 issued by the LST flow calculation block 36, reduces the consumption of LCT. Corresponding signals for decreasing or increasing the flow rate of LST are fed to the input of the controller 19 R _pl flow rate LST.

In block 37 for calculating water flow, the measured value 38 of moisture w at the outlet of Hydrofol is compared with a preset value 41 of moisture w, and, in addition, an additional correction of water flow is introduced into the algorithm for calculating water flow according to the measured value of slurry viscosity η.

The algorithm for calculating water flow works in the following sequence. If the measured value 38 of the moisture content of the sludge w is higher than the set value 41 and the value of the viscosity w of the sludge is lower than or equal to the set value 40 of viscosity, a signal 44 is generated in the water flow calculation unit 37 to reduce the water consumption. However, if the measured value of humidity 38 is lower than the set value 41 and the correction signal 39 characterizing the viscosity of the sludge η corresponds to a viscosity higher than the set 40, a signal to increase the water flow rate is generated in the block 37 for calculating the water flow.

The next control loop for the wet self-grinding process in the Hydrofol mill is the regulation of mill performance by continuously monitoring the density of sludge at the outlet of the mill unit.

It is known that sludge density determines the ratio of the content of solid and liquid components in the sludge, i.e. dry chalk, clay and water, while the lower the solids content in the sludge, the lower its density, and vice versa, the higher the solids content in the sludge, the higher its density. Thus, an increase or decrease in the density of the sludge with the same volume of sludge is proportional to an increase or decrease in the solid component in the sludge, and, therefore, this can be associated with an increase or decrease in the productivity of the mill.

In this regard, it is possible to regulate and maintain the maximum performance of the mill on the solid component. It is the determination of the density of the sludge, the determination of the amount of solid component in the sludge allows you to determine the most accurate performance of the mill. On the other hand, the measurement of sludge density allows the sludge moisture to be further determined by calculation.

The control loop and maintain the maximum performance, determined by the given density, works in the following sequence: in block 34 (Fig. 2) for determining the charge amount of chalk and clay, an additional correction signal 48 (Fig. 1) characterizing the density of the sludge and, accordingly, its content solid component. Figure 1 shows the formation of the correction signal 48, where it is seen that on the regulator 49 of the density of the sludge R _pt . job 50 sludge density, the measured value 46 of the sludge density coming from the meter 11, and the actual performance Q _sludge mill 47, determined by the flow meter 13. As a result of a comparison of the signals received on the regulator 49 in the calculation unit 34 (figure 2), the correction signal 48 providing in the calculation unit 34, a change in the load value depending on a change in the density of the obtained coarsely ground sludge.

Thus, the measurement and comparison of the chemical composition of chalk and clay at the inlet of the Hydrofol mill and the resulting slurry at the mill outlet with spectrometers 15 and 14, as well as the regulation of the ratio of the supplied components, makes it possible to stabilize and, therefore, optimize the chemical composition of coarsely ground sludge relative to a given quality criterion, for example, sludge titer.

Further, the measurement of viscosity and moisture of the sludge allows you to minimize the consumption of water and plasticizer LST and on this basis to reduce the moisture content of the sludge. Measuring the density and performance of the mill by sludge can increase the productivity of the wet self-grinding mill.

In general, the proposed method for controlling the process of wet self-grinding of sludge in a mill unit allows us to achieve our goal, namely, reducing energy consumption for the production of sludge and clinker from cement production, increasing the productivity of technological equipment, as well as improving and stabilizing the quality of coarsely ground sludge.

Information sources:

1. RF patent No. 2184615 dated 10/07/2002.

2. Auth. Testimonial. USSR No. 656662 class B02C 25/00, 1979.

Claims (1)

A method of controlling the process of wet self-grinding of materials in a mill unit, including measuring and controlling the amount of charge of the crushed materials, measuring the flow of water and plasticizer into the mill unit, characterized in that, in order to optimize the controlled parameters, reduce energy costs for grinding coarse slurry and clinker firing, and also stabilization of the quality of the resulting slurry, measure the viscosity and moisture of the slurry at the outlet of the mill unit, the chemical composition of the crushed materials at the mill inlet and outlet, the mill’s productivity and the sludge density at the outlet of the mill are additionally measured, and the flow of water and plasticizer LST are measured by the measured viscosity and moisture of the sludge, and the size of the milled materials is controlled by the measured values of the mill’s productivity and sludge density and according to the measured values of the chemical composition of the crushed materials at the mill inlet and the chemical composition of the sludge at the mill outlet, the ratio e and supplying comminuted material.

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