Vol 68 Iss. 1

Changes in the conductivity of a section of an electric circuit are widely used to measure ash content, moisture content, salt content and other parameters of solid, liquid and loose materials; this has made it possible to practically implement a number of measuring instruments and systems that have found wide application in the chemical, mining-metallurgical and other industries, as well as in the power industry and in scientific research. ...

Widely spread at concentration plants, the process of concentrate drying in rotating drying drums is a very complex object of automatic control. Therefore, the stabilizing automatic control systems (ACS) for these processes are also complex, multi-loop and multiply connected. The article attempts to determine the influence of various factors on the required accuracy of the ACS for drying being created, from the standpoint of the expected economic efficiency of these systems.

In the works of a number of researchers it has been shown that a satisfactory mathematical description of once-through flotation machines cannot be obtained without taking into account the effect of longitudinal mixing of the pulp, which is equivalent to turbulent diffusion and leads to an equation of the form.An exact description of convective mixing requires a specific mathematical apparatus. However, its absence makes it possible to raise the question of whether the diffusion equation can be used for these purposes, but on the condition that the diffusion coefficient is selected so that the mixing effect of the equivalent diffusion proves equal to the mixing effect of convection and diffusion acting jointly.

In resonant methods of moisture measurement, a capacitive sensor with the material under study is in some cases included in the oscillatory circuit of a self-excited oscillator. A change in the moisture content W of the material being monitored leads to a readjustment of the resonant circuit in the anode-grid circuit of the oscillator, which causes a certain increment in the generated frequency. The frequency increment of the self-excited oscillator is converted by frequency discriminators into a direct voltage, which is fed to a measuring instrument. A disadvantage of the considered method of moisture control is the dependence of the operating frequency of the self-excited oscillator on the magnitude of dielectric losses in the material being monitored. At large dielectric losses, the error in moisture measurement can reach significant values. This disadvantage also limits the use of highly sensitive resonant methods.

In the course of long-term operation of continuous moisture-measuring systems developed at the Department of Automation of Production Processes of the Leningrad Mining Institute, a significant influence on their operation was found to be exerted by the wear of the base and working electrodes of the sensor. ...

The drying drum as an object of automatic control was considered earlier. The main control actions in this system are the temperature and velocity of the drying agent, while the load (the flow rate of cake at the inlet) acts as the main disturbance. On the basis of the analytical synthesis performed, an operating model of the automatic control system (ACS) was built, which successfully passed tests and was accepted for implementation on all drying drums of the concentration plant of the Kovdor Mining and Processing Combine.

The task of fully automating the flotation process of apatite-nepheline ores proves to be very complex for a whole number of reasons. The study of the dynamics of the flotation process in a linear approximation can in principle be carried out by analytical methods using matrices of transfer functions.

In discrete rapid monitoring of the moisture content of dispersed materials, devices based on the E12-1A instrument, whose simplified circuit is shown in Figure 1, are in some cases used. The range and accuracy of moisture measurements of materials are determined not only by the design of the sensor, but also by the circuit of the measuring oscillator. The range of moisture measurement can also be extended and the effect of losses reduced by increasing the overall gain of the stage, for example, by replacing the cathode follower with an aperiodic amplifier with an anode load.

When constructing temperature-compensation circuits in capacitive moisture-measuring systems, it is necessary to take into account that the change in the temperature coefficient of capacitance (TCC) of the material being monitored may have a different character depending on its moisture content. Besides this, the circuit must automatically change the temperature-compensation coefficient in accordance with the change in the TCC.

With the increase in the share of deep vertical mine shafts in the mining industry and the corresponding increase in the speed of hoisting vessels and their load capacity, guides began to be subjected to dangerous impact loads associated with the interaction of the hoisting vessel with the shaft reinforcement. ...

In the process of operation, roadheaders tend to deviate from the specified direction. This is caused by mining-geological conditions, the machine design, and the specific features of operation. …

In a discrete moisture-measuring system of the F-meter type, the whole set of measurements of the capacitive component is brought to the calibration temperature in accordance with the temperature coefficient of capacitance of the material being measured...

The density of liquid products in the beneficiation of minerals is the most important parameter by means of which it is possible to influence and control the course of technological processes. The considered method of density measurement can be used as the basis for a continuous-action density meter, the use of which at a concentration plant will make it possible to improve control over the beneficiation process and thereby contribute to improving the quality and quantity of the finished product.

The main disturbing influence on mine air heaters and other heat objects (boilers, boiler rooms, water pipes, etc.) in the systems of automatic temperature control is the value of the increment of the outside air temperature over some constant interval of observation.

Selection and maintenance of optimal technological modes of preparation and briquetting, conditions of coal storage and transportation require prompt and objective automatic monitoring of its moisture content.

To control inertial objects, a control method based on introducing into the control action the derivative of the process, obtained in the form of a pulse repetition frequency, can be used. The method combines three-position control with a continuous control action based on deviation, and pulse control in the dead band of the three-position regulation.

The traditional approach to the study of sports technique is connected with instrumental methods of recording (kinography, cyclography, stroboscopy) of kinematic characteristics in order to reveal the kinematic structure, i.e. the correlation of movements in time and space. ...

The presence of people on a cargo **hoisting** vessel moving at high speed, especially on **the** skip, is prohibited by safety regulations. **A** circuit for automatically switching the measuring and recording equipment on and off based on magnetically controlled contacts has been developed at the Gipronickel Institute.

The accuracy of measurements of a capacitive moisture-measuring system essentially depends on the extent to which it is possible with its help to measure only the reactive component of the total conductivity of the sample being monitored. An effective method for reducing the error component of the moisture-measuring system (MMS) caused by the influence of active losses and other uncontrolled factors is to measure them and, on the basis of the data obtained, introduce a correction into the output signal of the system.

For mathematical modeling of the dynamics of the temperature regime of a horizontal converter, the starting point is the results of research into converter heat exchange in static modes. To obtain a simple model of dynamic regimes suitable for engineering applications, all the individual heat-transfer spaces are taken as lumped capacitances that accumulate heat.

Ensuring stable characteristics of the qualitative composition of mineral raw materials arriving for processing is one of the important directions of technical progress in the mining industry. In evaluating the effectiveness of averaging measures, in the general case the most acceptable turns out to be the proposed methodology based on the use of the apparatus of the theory of random functions.

Stabilization of the qualitative composition of processed mineral raw materials, as a rule, significantly improves technical and economic performance of the main technological processes and facilitates the introduction of automation and computer means for their control.

The problem of optimal coding of information texts largely determines the efficiency of information retrieval systems (IRS) and automatic control systems (ACS). The solution of this problem leads to minimizing the required computer memory capacity and increasing the speed of information retrieval.

The effect on the data transmission system (DTS) of various disturbing factors is of a random nature, so the time of transmission of a message of a certain volume is also a random variable. The timely delivery of necessary source data to the Information Processing Center and the provision of derived information to users within specified timeframes are among the key conditions for the effective operation of a mining enterprise’s automated management system.

Current control of the data transmission rate under ACS conditions serves for the automated evaluation of channels and is carried out on a computer by calculating the probability of successful transmission of a message format provided that correctly received blocks are recorded in the check section. ...

Improvement of the management of the national economy on the basis of wide application of economic-and-mathematical methods, the use of electronic-computing, organizational equipment and means of collection and transmission of information provides for the development and introduction of automated management systems (AMS) for industries, organizations and enterprises. ...

In conditions of large exposures of the roof, for example, when developing minerals by the chamber system (or chamber-longwall), information on mining-geological characteristics acquires particular importance. Timely support of anomalous roof zones will make it possible to substantially improve the safety of mining operations and ensure the possibility of working stoping faces up to the design span..

Linear asynchronous motors (LAM) are successfully used in transport abroad (in overhead cranes, in induction magnetohydrodynamic converters and on suspended monorails, which is of the greatest interest), and various circuits and control devices for transport installations are used. ...

Solving problems of operational monitoring of rock pressure parameters is connected with the necessity of obtaining a large volume of data on the stress-strain state of the rock mass and the support of workings. These data can be obtained promptly only with the use of special measuring apparatus, for example, that developed at the LGI. It makes it possible to receive information from a large number of various sensors located within the entire mine field at considerable distances from each other. As shown by pilot-industrial tests at the Mayak and Kaula-Kotselvaara mines, the effectiveness of such apparatus largely depends on metrological parameters.

The efficiency of operational-dispatch control during the implementation of the measures of the accident liquidation plan (ALP) largely depends on the accuracy, freedom from error and timeliness of the actions of the dispatcher – the responsible supervisor of accident liquidation. ...

Various methods of unloading ore from multi‑section hoppers provide opportunities for stabilizing the quality of the ore. The described scheme is characterized by high reliability and ease of operation, and can be used for ore blending at various mining industry enterprises.

A closed-loop system of automatic control consisting of a linear system with distributed parameters and one non-stationary nonlinear element is considered. …

Without the ordering of documentation, the unification of forms and the optimization of methods of recording and collecting information, the effective functioning of automated control systems is impossible. ...