Senkovskij Stanislav Aleksandrovich
Faculty
Institute of Mining and Geology
Department
Mineral Processing
Researches parameters of motion of the particles when the slurry particle size of the hydraulic regime
Scientific advisor
PhD, professor Nazimko Elena
Main page
The paper on a subject of final work
Сontents
2. Purpose and research problems
3. Review of researches and development
Introduction
Now gravity concentration is used for processing not one-two, and a number of minerals – from андалузита to zircon, from coal to diamonds, from mineral sand to oxides of metals and from production minerals to rare metals.
In spite of the fact that gravitational methods long since are widely used around the world for enrichment of many minerals, there is no exact science which could give model and the mathematical description of process. It is apparent that very heterogeneous inventory is used because of poor comprehension of processes of gravity concentration. During, a long time various researchers study the mechanism of action of this inventory; however the uniform theory of enrichment doesn't exist, and it can't be created.
The method of gravity concentration is based on distinction of nature of driving of grains under the influence of dynamic impacts of water jets on them. Division is carried out in inclined flows of small depth (thickness). Routinely depth of a stream doesn't exceed the 10-fold size of the maximal grain of an enriched mix. Many devices in which this principle of enrichment is used are known, but the main are: concentration tables, locks, screw separators, jet trench and jet concentrators, tapered separators.
Common for all is that driving of a pulp occurs on a sloping surface by gravity [1].
Concentration tables are applied to enrichment of shallow classes of ores, coal and anthracite, and also ore and coal slimes. Division on tables occurs in a stream of the water, flowing a shallow layer on the sloping plane.
Concentration tables share on fixed and the relative frame. The fixed tables are applied to processing gold-bearing and slimes on zolotoizvlekatelny and other ore dressing-works. The travel tables happen tape, round and shaking.
Shaking tables found the widest application at enrichment of various minerals [2].
The concentration table, isn't neither compact, nor high capacity inventory. However properly working concentration table can be one of the most efficient concentrating devices, capable to process a particle of very wide range of a krupnost with high extraction and extent of enrichment.
Concentration tables apply as when processing metallsoderzhashchy ores, and coals. For uniformity we will call the top party decks feeding party; нижнююсторону through which the light distillate unloads, – the tail party; the end through which the last cut unloads, – the kontsentratny end, and the end to which attached the mechanism, – the mechanical end.
Concentration tables – very flexible inventory also can be used in operations from the main separation to perechistny, for processing and sand and slimes, division of two heavy minerals and coal washing [3].
1. Subject urgency
Now there is a problem of enrichment of a material of a slime krupnost without use of flotation or decrease of loading by flotation process. Deterioration of a financial condition of the coal industry induces separators constantly and continuously to find rational technologies. On dressing-works of Ukraine it is for various reasons lost with a wastage to 960 thousand t. coal in a year. Therefore research of driving of a slime particle on an even surface in a water stream, on an example of a concentration table is an acceptable path to study methods of decrease of losses of coal weight in a wastage.
Important substantial source of padding fuel are a carbonaceous wastage and the zabalansovy slimes suitable for processing. By results of long-term works it is established that slimes of coal mines, ugleobogatitelny factories and ilonakopitel коксохимзаводов is perspective to use positions of their production processing.
Experience of development of ilonakopitel indicates possibility of receiving coal concentrates by ash content of 10-30 % at their exit of 30-40 % from processed raw materials.
2. Purpose and research problems
The purpose of the real work – a theoretical and pilot study of driving of a particle of a slime krupnost at change of hydraulic controls on an example of gravity concentration on a concentration table; studying of the factors influencing driving of particles, and finding of their optimal parameters.
For achievement of the formulated purpose the following tasks are put:
1. Studying of physics of driving of a particle in an aqueous medium on an even sloping surface.
2. Studying of parameters of a concentration table and its duties.
3. Carrying out researches of driving of a part of a slime krupnost of the different nature at change of parameters of a table.
4. The analysis of the received results and development of an optimal duty of inventory.
3. Review of researches and developmentк
In the modern practice at gravity concentration of shallow classes of ore and nonmetallic minerals concentration tables on which under the influence of the water flow, flowing on the sloping plane decks, gravity and asymmetric reciprocations decks there is a division of minerals on a specific gravity are applied.
Concentration process was carried out earlier on the fixed and travel tables which completely went out of use now in view of their small efficiency and are replaced with shaking tables [5].
Concentration tables found a wide spread occurance at enrichment of tin, tungsten, redkometalny, auric ores by a krupnost from 3 to 0,04 mm, and also coals a krupnost less than 10 mm.
The general view of a concentration table is shown on fig. 1 [1].
Fig. 1. Concentration table
Shaking concentration tables consist of the following basic elements:
1. Decks (planes) with the laths (grooves) attached on it feeding and switching centers; on a deck there is a material division on specific gravities;
2. The basic device and the mechanism regulating a cross inclination decks;
3. Receiving devices for products of enrichment unloaded about decks;
4. The drive mechanism, reporting a deck continuous asymmetric reciprocation [5];
The modern type of a concentration table is represented on fig. 2.
Fig. 2 Concentration table
The material subjected to enrichment, entering on a table, it is distributed on a surface decks. Under the influence of differential driving and gravity the last is stratified between narifleniye. Stratification is accompanied by moving of layers from top to down under the influence of a water cross flow as the stratified bed moves towards the exhaust end. The water flowing across decks, partially enters together with initial coal, is partially brought separately through a trench located along the top edge of a table. Gradual removal of an enriched material, since high layers in the direction to a surface decks, occurs thanks to decrease of height of narifleniye to the exhaust end of a table. Thus, more penetrating lying layers of a material communicate under the influence of a water cross flow as the material which has settled between grooves comes nearer by the table end. Here on a surface decks there is only a layer which thickness doesn't exceed diameter of one or two grains of coal. This layer eventually also unloads at the end of a table, routinely already on a cross edge decks [4].
The arrangement of various grains on a deck of a table becomes fan-shaped fig. 3.
Fig. 3. A fan-shaped arrangement of grains on a table deck:
A – a concentrate; В – промпродукт I; С – промпродуктІІ; D – tails of I; E – otvalny tails; F–slimes;
At enrichment of coals in feed zones of unloading (from a drive) settle down the largest and lightest grains, in the subsequent zones the granular size decreases, and their density increases.
During advance of a suspension of grains after a deck of a table there is a loosening, its stratifying and selective transportation of grains according to their density, a krupnost, and also a form.
Particles of high layers of a stream when driving after a table deck sequentially get to mezhrifelny intervals where there is their repeated stratifying. When driving grains along mezhrifelny channels towards unloading of heavy grains (to the face party decks the height of narifleniye decreases) the washing water cross flow follow-up washes away light grains, i.e. there is a concentrate cleaning.
Thus, on a concentration table there is a posleyodovatelny multiple repetition of process of concentration in intervals between grooves and at the same time padding concentration of the stratified heavy material at its fan-shaped driving to unloading [1].
Types of movements of the mineral particles being in the current stream:
* driving on the bottom decks or to the postponed grains;
* driving faltering and fluidized and spasmodic;
* driving continuous and fluidized;
Three types of driving specified above are caused by forces of a hydrodynamic origin: one, directed along a current, another, directional from below up, and gravity of the particle directed from top to down [5].
Список источников
1. Шохин. В.Н. Гравитационные методы обогащения / В.Н. Шохин, А.Г. Лопатин. – М.: Недра, 1980.
2. Фоменко Т.Г. Гравитационные процессы обогащения полезных ископаемых / Т.Г. Фоменко. – М.: Недра, 1966.
3. Берт Р.О. Технология гравитационного обогащения / Р.О. Берт. – М.: Недра, 1990.
4. Bird B.M. Coal preparation / B.M. Bird. – New York, 1950.
5. Исаев И.Н. Концентрационные столы / И.Н. Исаев. – М., 1962.
6. Благов И.С. Справочник по обогащению углей / И.С. Благов. – М., 1984.
7. Благов И.С. Обогащение углей на концентрационных столах / И.С. Благов. – М., 1967.