RU2726808C1 - Method of crushed stone production from iron ore beneficiation wastes - Google Patents

Abstract

FIELD: construction.SUBSTANCE: disclosed invention relates to production of construction materials and secondary use of industrial wastes, more specifically iron ore beneficiation wastes. Proposed method comprises dry magnetic separation of said wastes with separation into magnetic and nonmagnetic rocks. Enrichment wastes with iron content of not more than 16% and fractions of constituent fractions of not more than 300 mm are subjected to dry magnetic separation. Crushed rock is obtained from magnetic rocks selected during separation, which are subjected to sieving with removal of particles of less than 5 mm. Dry magnetic separation is carried out directly at the outlet of the iron ore beneficiation process line. Dry magnetic separation is carried out using a magnetic separator of drum type. Screening is performed on the screen with simultaneous separation of crushed rock by fractions. Optimal fineness of fractions of enrichment wastes supplied to dry magnetic separation is 0–70 mm. Preliminary dry magnetic separation of enrichment wastes is subjected to grinding.EFFECT: providing simple and fast cleaning of ore tails from weak rocks to obtain quality crushed stone.6 cl, 3 ex, 2 dwg

Description

The technical field to which the invention relates

The invention relates to the production of building materials and the field of secondary use of industrial waste, more specifically, iron ore dressing waste.

State of the art

The classical technology for obtaining construction crushed stone includes a mining stage, which involves drilling wells in rock for laying an explosive, blasting and transporting destroyed rocks using heavy equipment to the place of subsequent processing, including crushing (crushing) the raw material to acceptable parameters and separating into fractions by means of screens. This technology for the production of crushed stone is costly, energy-intensive and leads to the depletion of natural resources.

It is known to produce crushed stone from associated (overburden) rocks obtained during the extraction of ore materials, which allows saving on the stages of extraction and transportation of raw materials. The method of producing crushed stone, in this case, includes stepwise crushing of associated (overburden) rocks, followed by separation into fractions and passing them through a magnetic separator to separate ore from crushed stone, which is sent to the production of iron ore concentrate (book. Building materials from industrial waste. Dvorkin L .I., Publishing house: Rostov-on-Don, "Phoenix", 2007, p. 299-300).

A known method of producing crushed stone (see patent RU 2232057, IPC: В03С1 / 00, publ. 10.07.2004), including multistage grinding of iron ore and dry magnetic separation with the release of a magnetic product, which is sent to wet magnetic enrichment, and the non-magnetic product - waste of magnetic separation is sent to the crushed stone warehouse.

In fact, the waste of dry magnetic separation, which is proposed to be used as crushed stone in the patent RU 2232057, is waste of the iron ore beneficiation process, the so-called ore tailings (hereinafter - tailings).

The tailings are composed of waste rock and off-grade ore with a low mineral content and have a relatively uniform grain size distribution. Their use would allow solving the existing problem of crushed stone shortage and at the same time preserving natural resources.

However, crushed stone obtained by the method according to patent RU 2232057 from iron ore dressing wastes, like crushed stone obtained by the above method from overburden, only in rare cases has the desired quality and meets regulatory requirements that allow it to be used for construction needs, namely in cases of absence in the original ore of weak rocks or their insignificant content.

At the same time, as practice shows, often the original ore contains a large amount of weak rocks, represented by various clay minerals, minerals unstable to weathering processes, inclusions of asbestos, mica, coal, peat, plant soil and other organic substances. All these "weak" impurities after separation of iron-bearing rocks (magnetic product) remain in the non-magnetic part (waste) and the use of such waste as construction crushed stone without additional purification is impossible or severely limited.

Grains of weak rocks are characterized by a compressive strength in a water-saturated state of less than 20 MPa, while when they are separated, according to GOST 8269.0-97 "Crushed stone and gravel from dense rocks and industrial waste for construction work", they are guided by the following distinctive features: grains Weak rocks are easily broken by hands and destroyed by light hammer blows, on the surface of which, when scratched with a needle, a trace of a steel needle (on the surface of grains of igneous and metamorphic rocks) or aluminum (for grains of sedimentary carbonate rocks) remains. Those. in fact, the identification of weak rocks is done visually and manually.

To separate light and clayey "weak" impurities, water can be used to ensure their dissolution and precipitation. However, in this case, the device of special sedimentation tanks is required, which significantly increases the cost of crushed stone production and makes it unprofitable.

As a result, iron ore dressing wastes, which are not widely used, accumulate for years in dumps, occupying huge areas. In this regard, the issue of utilization of waste from mining and processing plants has become increasingly acute lately.

As the closest analogue for the claimed technical solution, a method for processing waste of iron ore production was adopted, aimed at maximizing the extraction of useful products with the associated production of construction and ballast crushed stone, disclosed in patent RU 2190027, IPC: С22В 1/00, В03В9 / 06, publ. September 27, 2002.

The method according to patent RU 2190027 includes gravitational enrichment by waste segregation with the separation of individual fractions, which are subjected to magnetic separation, first low-gradient, then high-gradient, with the release of substandard magnetic product (magnetic rocks) and construction rubble (non-magnetic rocks) at intermediate stages.

Signs of the closest analogue, similar to the essential features of the proposed method, are that the waste of iron ore beneficiation is subjected to dry magnetic separation with separation into magnetic and non-magnetic rocks.

The closest analogue has the same disadvantages as the previous analogs, namely the impossibility of obtaining high-quality crushed stone from ore dressing wastes with a high content of weak rocks.

The claimed invention is aimed at solving the problem of obtaining high-quality crushed stone from iron ore dressing wastes with a high content of weak rocks.

The technical result is expressed in providing the possibility of simple, quick and low-cost cleaning of ore tailings from weak rocks with obtaining high-quality crushed stone.

Disclosure of the essence of the invention

The solution to the above technical problem is provided due to the fact that in the method for producing crushed stone from waste of iron ore, including dry magnetic separation of this waste with separation into magnetic and non-magnetic rocks, according to the claimed invention, the waste is subjected to dry magnetic separation with an iron content of not more than 16% and the size of the constituent fractions is not more than 300 mm, while the crushed stone is obtained from the magnetic rocks selected during the separation, which are sieved with the removal of particles less than 5 mm.

The proposed method makes it possible to simply, quickly and with minimal cost clean up ore tailings from weak rocks, and at the same time from clay and organic impurities, thereby obtaining high-quality crushed stone that meets regulatory requirements.

Unlike other known solutions aimed at separating weak rocks, the proposed method provides for the isolation of hard rocks, while its magnetic properties are used as an estimated indicator (indicator) of rock strength.

Using dry magnetic separation, strong iron-containing rocks are distinguished, which differ in their magnetic properties, and it is they that are subjected to sieving with the separation of small particles and obtaining marketable crushed stone.

Iron-bearing rocks are fairly hard rocks with a strength factor f equal to 6 on the strength scale of prof. Protodyakonov, due to which the resulting crushed stone meets the standard strength requirements.

Most of the weak rocks (as shown by tests - almost completely) remains in the non-magnetic fraction and must be removed to the dump. As a result, the resulting crushed stone meets the regulatory requirements for the content of grains of weak rocks.

Together with the weak rocks, clay particles, clay lumps and organic impurities are removed, which also do not have magnetic properties and remain in the non-magnetic fraction.

Thus, the crushed stone obtained by the proposed method from iron ore dressing wastes containing weak rocks meets all regulatory quality requirements and can be widely used for the construction of highways and other types of construction work, where there are no restrictions on the iron content.

The authors of the present invention, the separation of weak rocks from ore tailings, using the sign of their lack of magnetic properties, is new and unknown from the prior art.

The proposed method can be used both for processing ore tailings accumulated in dumps, and for newly formed enrichment wastes.

The proposed method can be easily integrated into the general technological scheme of iron ore beneficiation by placing a device for dry magnetic separation at the outlet of the processing line, mainly a drum-type magnetic separator, and a screen (or other device) for removing fine particles up to 5 mm and separating crushed stone into factions.

Such integration will significantly reduce the volume of waste sent to dumps, and hence the costs of the enterprise associated with loading and transporting waste.

The use of enrichment wastes with an iron content of more than 16% to obtain crushed stone is not economically viable. The control of the iron content in the tailings is carried out at mining and processing plants in a known manner.

The use of enrichment wastes, represented mainly by fractions of more than 300 mm, is impractical, because in this case, the yield of crushed stone is very low, which makes its production unprofitable.

The optimum size of the enrichment waste fractions supplied to dry magnetic separation is 0-70 mm, which corresponds to the maximum output of crushed stone.

Tailings, consisting mainly of coarse fractions, are expediently subjected to grinding before being fed to dry magnetic separation.

Implementation of the invention

The proposed method was implemented at a mining and processing enterprise for the production of iron ore concentrate and iron ore pellets of JSC SSGPO Sokolovsko - Sarbayskoye mining and processing production association, Rudny, Republic of Kazakhstan.

The Sokolovsko-Sarbayskoe deposit is represented mainly by magnetite ores, which occur in the Lower Carboniferous volcanic-sedimentary rocks (volcanic breccias, tuffs, andesite porphyries, limestones and calcareous tuffites) and are overlain by Mesozoic sandy-clayey sediments.

The result of the concentration of such ores is waste (otherwise - tailings) with an iron content of up to 16% and a content of weak rocks of more than 30% (in specific examples, measurements showed: 32.7% and 36%).

The use of such tailings as construction crushed stone is impossible, due to the fact that the content of weak rocks in them is several times higher than the permissible standard values, which, according to GOST 8267-93, 3344-83, 7392-2014, are 5 or 10%, in depending on the brand of crushed stone and its scope.

The possibility of processing tailings containing weak rocks, with obtaining high-quality construction crushed stone, is realized through the proposed method.

The essence of the invention is illustrated by drawings, which show:

figure 1 is a general technological scheme for producing crushed stone from iron ore dressing wastes, which implements the method;

in fig. 2 is a process flow diagram of crushed stone production located at the outlet of the iron ore processing line.

The technological scheme for producing crushed stone from iron ore dressing wastes includes (see Fig. 1) a magnetic separator 1 for dry separation, located at the outlet of the belt conveyor 2, and a screen 3.

For the implementation of dry magnetic separation can be used a separator of any known type, for example, see the book. Beneficiation of ores. Polkin S.I., M: Metallurgizdat, 1953, pp. 611-632.

In a specific embodiment, a magnetic separator "MAGNIS" KMR-1,8 / 2.0S, drum type, installed as a drive pulley of the belt conveyor 2, was used.

The separator drum is a hollow cylinder with a diameter of 1800 mm with a battery of permanent magnets inside, which provides a magnetic field strength on the drum surface up to 3000 Oersted.

This magnetic separator allows the processing of raw materials up to 350 mm in size and has a capacity of up to 500 tons / hour, adjustable by the drum rotation frequency.

Magnetic separators with electromagnets, which can also be used in the implementation of the method, have wider possibilities, for example, the ability to control the magnetic field strength.

The method is carried out as follows.

Waste from the enrichment of iron ore (hereinafter - tailings) 4 by means of a conveyor 2 is fed into the zone of action of a magnetic separator 1.

Getting into the magnetic field of the separator 1, mineral grains of hard rocks, containing iron particles, are attracted to the drum surface and move with it until they leave the magnetic field, which provides their trajectory of movement that is different from the trajectory of movement of mineral grains of weak rocks, characterized by a low magnetic susceptibility, which do not interact with the magnetic field of the drum and move along a trajectory that depends only on the action of mechanical forces.

As a result of the difference in magnetic properties, the tailings are separated into hard rocks - magnetic fraction 5, and weak rocks presented in non-magnetic fraction 6.

Along with weak rocks, non-magnetic fraction 6 contains clay particles, clay lumps, and various organic inclusions.

Non-magnetic fraction 6 is removed by conveyor 7 to the storage area, from where it is sent to dump 8.

The magnetic fraction 5 is sieved on a screen 3. This removes small particles up to 5 mm, this is the so-called screening, and the crushed stone is separated into crushed stone fractions.

In FIG. 2 shows an example of the integration of the method into the existing technological scheme of iron ore beneficiation. In this case, the magnetic separator 1 is placed at the outlet of the ore processing line, indicated by pos. nine.

Example # 1.

Waste enrichment with a particle size of 0-70 mm was processed.

The yield of magnetic fraction 5 after separation was 61.8% of the total amount of ore tailings at the entrance to separator 1.

The screening out (fraction 0-5 mm) after screening 3 was 17.5%.

Example No. 2.

Waste enrichment with a particle size of 0-150 mm was processed. The yield of magnetic fraction 5 after separation was 50.7% of the total amount of ore tailings at the entrance to separator 1.

The screening out after screen 3 was 15.2%.

Example No. 3.

Waste enrichment, consisting mainly of large particles up to 300 mm, was subjected to processing. The yield of the magnetic fraction 5 after separation was 32.6% of the total amount of ore tailings at the entrance to the separator 1. The screening after the screen was 16%.

As can be seen from the examples, the optimal size of the enrichment wastes used to obtain crushed stone is a size of 0-70 mm, since in this case the greatest output of crushed stone is provided.

Larger waste enrichment, preliminary separation, it is advisable to subject an additional operation - grinding (pos. 10 in Fig. 2).

As can be seen from the above examples, taking into account all the removed fractions, the proposed method makes it possible to reduce the waste of the mining and processing plant sent to the dump by almost half.

The proposed method is very simple and requires a minimum of capital investments, providing a low cost of the resulting crushed stone.

As the studies have shown, the crushed stone obtained from the processing waste meets all regulatory requirements, including the requirements for strength and grain content of weak rocks, which was less than 1%.

Such crushed stone can be widely used in construction, for example, when erecting buildings, arranging highways, to create a ballast layer for a railway track, etc.

Claims (6)

1. A method of producing crushed stone from iron ore dressing wastes, including dry magnetic separation of these wastes with separation into magnetic and non-magnetic rocks, characterized in that dressing wastes with an iron content of no more than 16% and a size of the constituent fractions of no more than 300 mm are subjected to dry magnetic separation , while crushed stone is obtained from selected during the separation of magnetic rocks, which are sieved with the removal of particles less than 5 mm. 2. The method according to claim 1, characterized in that the dry magnetic separation is carried out directly at the outlet of the iron ore processing line. 3. A method according to claim 1, characterized in that the dry magnetic separation is carried out using a drum type magnetic separator. 4. The method according to claim 1, characterized in that the sifting is performed on a screen with simultaneous separation of crushed stone into fractions. 5. The method according to claim 1, characterized in that the optimum size of the enrichment waste fractions fed to the dry magnetic separation is 0 - 70 mm. 6. A method according to claim 1, characterized in that the enrichment wastes are subjected to grinding before dry magnetic separation.

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