INTRODUCTION

    High efficiency of coal mining depends to a considerable degree on accuracy and reliability of mine conveyor transport operation the significance of which is becoming more essential in connection with the remoteness of mining faces from mine loading bores.

    As far as the extent of conveyor lines is increasing, problems connected with reliability and their safe exploitation are of great importance. The role of automation of mine conveyor transport consists in reduction of a labour coefficient of servicing, releasing the employees whose work is connected with the underground transport as well as improving of safety and reduction of injuries. The last one is achieved by introduction of necessary shields and block systems, and expanding of information capacities of automation apparatus.

    In connection with the development and stimulation of mining, the conveyor transport becomes more widespread (as the main kind) which in certain cases is a unified complex consisting of a chain of conveyors from the face to the mine surface. State-of-the-art main conveyor lines have a substantial extent, high productivity and are characterized by the usage of powerful multimotor conveyors (the capacity of drive can reach 500 kW and sometimes 1000 kW, they are used for the purpose of transporting of both cargoes and people).

    OBJECTIVES AND TASKS

    In conveyor transport automation it is very important to use a centralized control of drives of conveyor units having an automatized start-up. The main point of such control is that the operator performs activation of the engine of the first conveyor only, and the engines of other conveyors start-up in a specified succession automatically.

    All these problems can be solved under the use of brand new technologies and solutions in automation apparatus schemes - microprocessors and microcomputers, mathematical software which could be adjusted to different conditions of mining that were not taken into account while projecting the mine. Facilities and systems providing microcomputerized control of processes according to models and algorithms allow to manipulate the parameter values, to forecast the process dynamics and to simulate industrial situations for the purpose of searching the most optimal situations (according to control criteria having been accepted) under definite conditions and within the ultimate target task.

    One of the promising directions of improving the existing systems of repair and maintenance is the method of repair according to actual operating conditions, in other words with obligatory periodical or regular diagnostic analysis of operating conditions.

    A new automatic control system (ACS) for mine conveyor transport must ensure:

    - the growth of productivity of mining operations;

    - the reduction of power consumption;

    - the increase of the quality of coal being drawn;

    - the fail-safe operation of conveyor line in whole.

    The objective of the work is to work out new systems of automation on the basis of existing ones which could satisfy in complex the requirements having been put forth to ACS.

    For a successful realization of the objective of the work it is necessary to make appropriate mathematic models and to analyze physical processes that take place in the object on the base of modern computer programs and methods of calculations.

    SCIENTIFIC NOVELTY

    At the present time there is no special complex apparatus to analyze the operating conditions of the main conveyor lines that are characterized by a considerable extent. In the work it is suggested to examine physical phenomenon taking place in mining equipment in case of incident, to work out some recommendations relating to improving of elements and algorithms of automatic control system and to perform measurements of the most important technological parameters in proper time and authentically with the help of existing and available technologies.

    PRACTICAL VALUE

    The level of perfection and reliability of all kinds of protection exercises a significant influence upon safe operation of conveyor lines as well as safe mining. Technological schemes of conveyor lines are different; their character is defined by mine technical conditions and modifications of conveyors being used.

    Application of diagnostic methods and facilities in the system of repair and maintenance will allow to obtain an affordability as a result of the exclusion of equipment disassembling and assembly procedures, the reduction of equipment downtime. Automation of conveyor transport provides equipping of each conveyor with automatic control and protection means and functioning under the given algorithm of some conveyors and the whole chain.

    RESEARCH RESULTS

    Problems of control and production must be examined on the basis of the conception about prospective development of an enterprise taking into account technological, technical, organizational, industrial and economic aspects.

    Transport complex is considered to be the object of automation which delivers mineral resources from mining faces to the surface of the mine and includes conveyor transport with storage bunkers and skip hoisting. Control of conveyor line operation is carried out according to algorithm and must ensure the most optimal (under the conditions of energy saving) ratio of “belt loading level – rate of belt speed - bunker loading level” without a restriction of face capacity.

    In case of absence of the material on the belt, the conveyor must be stopped. These measures will allow to reduce energy consumption due to minimization of conveyor free-running as well as to increase the lifetime of a rubber belt.

    Existing at present systems controlling mine conveyor facilities do not allow to regulate the moving speed of the belt effectively and so to influence energy consumption by a conveyor facility.

    To realize the criterion of control, a generalized structural scheme of automatic control system of mine transport is given in picture 1.

    Picture 1 - The generalized structural scheme of automatic control system

    On the lowest hierarchical level of the system the selection of information from initial measuring conversion devices, discovering of technological parameter deviations from the specified ones, control and prognostication of preaccidents, protective and regulating functions along with the usage of actuating mechanisms are performed by means of local automation of type ÀÓÊ.1Ì.

    On the middle hierarchical level the microcontroller in accordance with the algorithm performs the realization of controlling functions under the criterion of effective regulation in the specified cycle of data averaging interval, optimizes certain technological zones and adjusts the structure and settings of regulators of direct digital control to the changes of operating procedure dynamics.

    On the highest hierarchical level a microcomputer operator (personal computer) collects and processes information having been received from a microcontroller (or a group of microcontrollers) of the middle level and according to the results the decisions are made in organization, synchronization and coordination of interaction of power-operated equipment which is included into mine transporting complex. The highest hierarchical level is on the surface of the mine in immediate proximity to the mine traffic controller who regulates the work of the entire complex in whole. The communication with elements of the lowest hierarchical levels which are very close to the objects of automation is executed with the help of means of telemechanics.

    After launching of a conveyor line by apparatus ÀÓÊ.1Ì a device controlling the conveyor line starts to work and regulates the chain according to the specified algorithm against the time of the day. The aim of controlling lies in blackout of conveyors and all the technological equipment when there are morning (from 7:00 till 9:00) and evening (20:00 till 22:00) peaks of energy consumption. Besides, in the process of mining operations a regular control of presence of the material on the belt and in the bunker is carried out, and for the purposes of energy saving the deactivating/activating procedures of certain equipment of the transporting chain is carried out.

    The new system of automatic control of mines conveyor transport which is being developed will provide:

    - the increase of productivity of mining due to the reduction of downtime of the main conveyors;

    - the decrease of energy consumption and tear and wear of the equipment due to the reduction of free-running of conveyor arms;

    - the improvement of the quality of the coal being drawn by the mine due to selective extraction of coal and rock out of mining and preparatory faces.

    CONCLUSIONS

    The device controlling the conveyor line which is being developed provides the uniformity of traffic being received by means of regulation of conveyor load-bearing element (belt), activating and deactivating of necessary blocking systems; it satisfies all the requirements relating to explosion safety for facilities which are used in coal and shale mines, all the component cells and elements of the facilities are unitized and interchangeable. The realization of a suggested structural scheme in unified system of automatic control of underground transport complex of mines will allow to increase the effectiveness of its functioning due to the reduction of downtimes, unforeseen breakdown of the equipment, nonproduction energy consumption especially at the time of peaks of energy consumption.