Engineering science/2. Mechanics

Malybaev S., Togizbaeva B.

The Karaganda state technical university, Kazakhstan

Working out of recommendations about consecutive release small ores

This work is devoted interaction questions small ore and the bunker with the account fiziko - mechanical properties of ore weight and service conditions of the concentrating factories applying as heat-sink capacity special supersize bunker.

Supervision and the statistics shows that because of loss of flowability of ore weight of the bunker are unloaded not completely, volume not unloaded weight makes (35 … 40) %.

As a result, because of losses of time for bunker clearing productivity of mills of the first stage of crushing on (10 … 30) % decreases. Time of idle times of main case OF makes (25 … 35) % of planned time of their work.

The carried out critical analysis of the basic means of struggle with the stuck small ores in bunkers has allowed to establish ores that and use means of clearing of mechanical type because of a number of their advantages have a wide scope: simplicity, compactness, sufficient safety in operation, low cost of manufacturing, simple service etc.

Known devices were applied to achievement of the greatest effect of clearing of bunkers, namely fingers, scrapers and others.

However, application of the existing designs preventing the stuck small ores in the bunker, has not led to positive results.

Theoretical and experimental researches of processes of loss of flowability of ore weight for the purpose of working out of ways of effective struggle with the stuck small ores show that it is necessary to create new designs of the devices providing reduction of durability of caking. These devices should include change of operational parametres of the bunker (increase in productivity of an unloading, maintenance of full unloading of the bunker and change of parametres of a final aperture, etc.), application of a baking powder and consecutive release of ore.

By results of the executed researches we develop the designs allowing substantially to prevent loss of flowability of ore weight. The analysis of existing ways and means of increase of flowability of ores ths of weight in bunkers of mountain-concentrating manufacture has shown that in character and to action they can be divided on two basic groups. The first group is ways of prevention of caking of ore weight and the second - is ways of removal of a packed material. But these ways at-are suitable only for coal or for well loose material.

In this connection there was a work object in view: creation of ways and means on flowability restoration small ores on the basis of maksimal th account of interrelations physico– mechanical characteristics ore mas-sy and parametres bunker.

For object in view achievement following problems were solved:

1. An establishment of law of caking small ores depending on various physico - mechanical properties and definition of their limiting values.

2. Working out mathematical models of influence of the basic operational factors and physicomechanical properties ore mas-sy on stuck it in the bunker.

For object in view and decision achievement problems-whether are executed analytical and experimental researches.

Researches of interrelation of characteristics of flowability small ores: initial resistance to shift and a corner of an internal friction with fractional structure, humidity and a storage time were spent with use tribometr by R.Zenkova's technique, on the modelling bunker. For reception of authentic results of experiments it was necessary to spend not less than 6 independent repeated experiences.

Because the most adverse conditions are: presence small ore fractions, storage period in the bunker of a loose material, humidity, pressure in experiments have been accepted the worst conditions, that is their limiting values, for convenience of the analysis and comparison of results.

As a result of experiment researches dependences are received. Here it is visible that the greatest initial resistance are received under following conditions: humidity W=12 of %, fractional structure of 0,5 mm - of 1 mm, time 24 hours.

The optimum mode of operation which consists in the following has been developed for achievement of full unloading of the bunker and maintenance of rhythmical work of the equipment of concentrating factory.

The bunker is necessary for unloading through one final aperture, instead of through two or three as it becomes now. After have let out small ore through the first aperture, ore through the second and so yet all section from five releases until then will not be unloaded consistently is issued. Throughput of one final aperture Q_о, м³ / hour that much more necessary Q_м, м³ / hour. It means that it is possible to provide a food of a mill of the first stage of crushing letting out small ore through one final aperture. To unload this part of the bunker it is possible through time t.

When final apertures consistently unload, it is necessary to load consistently a part of section of the bunker over the released final apertures.

Thus, repeatedly the first final aperture will unload through time tс. This time of full unloading of the bunker of the main case of concentrating factory №1 on one mill. Time of a total load of the bunker at the reached productivity of crushing case KD-1 (Q_к, м³ / hour), will be equal

где Q_к - productivity of the crushing case;

М_с - weight small ores in one section.

That is, through everyone t₃ hour the bunker will unload completely at serially working final apertures. Thus the crushing case under any circumstances will have time to load the bunker.

Thus, the operating ratio for all final apertures will be approximately identical as updating of loaded ore on all useful area of the bunker constantly is supposed.