RU2632788C1 - Method for dressing iron-containing ores - Google Patents

Abstract

FIELD: mining engineering.

SUBSTANCE: method includes several grinding stages, wet magnetic separation of ground products of each stage with production of middlings and waste tailings and with production of concentrate by means of wet magnetic separation after last grinding stage. The middlings after the first grinding stage are separated by magnetic properties to produce magnetic and medium-magnetic products. The medium-magnetic product is ground and dressed by wet magnetic separation in several stages with production of waste tailings and concentrate after last grinding stage. The magnetic product is ground in a separate second stage and dressed by wet magnetic separation to produce second concentrate and waste tailings. The second concentrate is ground in a separate third stage and dressed by wet magnetic separation to produce a high-quality concentrate and waste tailings.

EFFECT: increased efficiency of iron-containing ores dressing, improved quality of the iron concentrate.

3 cl, 5 dwg, 2 tbl

Description

The invention relates to the concentration of iron ores and can be used in the mining and metallurgical industries.

A known method of enrichment of iron ores, including two stages of grinding, wet magnetic separation (MMS) of crushed products of each stage to obtain tailings, industrial product after the first stage of grinding and concentrate after the second stage of grinding. From the wet magnetic separation by-products after the first and second grinding stages, the revealed highly magnetic magnetite grains are isolated into final concentrates by means of a wet high-selectivity magnetic separator [1].

The disadvantage of this method is its low efficiency, due to the low yield of strongly magnetic product (final concentrate) obtained after the first grinding stage. This is due to the insufficient amount of wet magnetic separation in the intermediate product after the first grinding stage of the revealed strongly magnetic magnetite grains, especially when using rod mills in the first grinding stage. In addition, the separation of strongly magnetic magnetite grains into the final concentrate from the by-product of wet magnetic separation after the first grinding stage requires the use of a special high-selectivity wet magnetic separator. The high selectivity separator [2] has a complex structure, which increases its cost and operating costs.

The closest in technical essence to this method is a method for the concentration of iron ores, including wet grinding of the initial ore in several stages, wet magnetic separation of the crushed products of each stage to obtain tailings and industrial products and to obtain the finished concentrate using wet magnetic separation after the last grinding stage [3, 4]. This enrichment method is used in almost all iron processing plants and is adopted as a prototype. The method of beneficiation of iron ore with crown by grinding stages (using a rod mill in the first stage), adopted as a prototype, is shown in FIG. one.

The disadvantage of the prototype is its low efficiency, due to the fact that the magnetic product (industrial product) obtained after the first grinding stage, containing a strong magnetic fraction (open grains of magnetite), a magnetic fraction (rich splices) and a medium magnetic fraction (poor splices), enters entirely the subsequent grinding stage, in which the magnetite grains are regrind and slurry. At the same time, the quality of the final concentrate is reduced due to the thin sludge of rock minerals and intergrowths, which fall into the flocs formed by magnetite particles and rich intergrowth particles. In addition, rock particles, both large and small, that fall into the flocs and are not removed into the tailings by wet magnetic separation and deslamination, fall into the mills of the second and third stages of grinding, which reduces the productivity of the grinding cycles and the concentration plant as a whole and leads to an increase in the cost of concentrate.

The objective of the invention is to reduce the cost of the finished concentrate (dependent paragraph 2 of the claims) or to improve the quality of iron concentrate (dependent paragraph 3 of the claims). The first problem is solved by separating the intermediate product after the first stage of grinding according to magnetic properties into magnetic and medium magnetic products and by subsequent separate grinding and enrichment of the magnetic product in one stage, and the medium magnetic product in several stages, which reduces the volume of mills for grinding the magnetic product. The second problem is solved by separation of the intermediate after the first stage of grinding according to magnetic properties into magnetic and medium magnetic products and due to subsequent separate grinding and enrichment in the second and third stages of magnetic and medium magnetic products, which provides a more complete disclosure of ore and rock grains and a more complete conclusion into dump tailings of rock particles.

This is achieved by the fact that in the method of beneficiation of iron ores, including several stages of grinding, wet magnetic separation of the crushed products of each stage to obtain intermediate products and tailings and to obtain concentrate using wet magnetic separation after the last grinding stage, the intermediate after the first grinding stage is divided into magnetic properties to obtain magnetic and medium magnetic products, the medium magnetic product is crushed and enriched using wet magnetic separation in several stages to obtain tailings and concentrate after the last grinding stage (Fig. 2). To reduce the cost of the concentrate, the magnetic product is ground and enriched in a separate second stage to obtain a second concentrate and tailings (Fig. 3). To improve the quality of the iron concentrate, the second concentrate is crushed and enriched in a separate third stage to obtain high-quality concentrate and tailings (Fig. 4).

As a result of separation according to the magnetic properties of the intermediate product of wet magnetic separation after the first grinding stage, a magnetic product is richer in iron and a medium magnetic product is poorer in iron (Fig. 2). The magnetic separation results of the MMC-I intermediate product after the first stage of core grinding of titanomagnetite ore into magnetic and medium-magnetic products in a drum separator with an increased bath depth, showing the possibility of increasing the iron content in the magnetic product, are given in Table 1.

After the first stage of grinding magnetite ore in a rod mill, the MMC-I intermediate product has a fineness of -3 + 0 mm and mainly contains rich and poor intergrowths of magnetite with rock minerals. The content of pure magnetite and rock grains in the intermediate product is insignificant, since a smaller particle size is required to reveal magnetite, and the grains of the rock minerals are removed to the tails using the MMC-I operation.

When the MMC-I intermediate product is divided by magnetic properties, the magnetic product will contain mainly rich splices, and the medium-magnetic product will contain mainly poor splices. For this purpose, you can use, for example, a drum magnetic gravity separator with an increased bath depth [5].

A magnetic and richer product obtained after the first stage of grinding and magnetic enrichment contains rich intergrowths of magnetite with rock minerals; therefore, to obtain further concentrate from it, it is necessary to grind and enrich it in only one stage. This will reduce the regrinding and sludging of magnetite contained in a magnetic and richer product, and will result in a finished concentrate from a magnetic product using only one grinding step (dependent claim 2, FIG. 3). In this case, the first concentrate is obtained from the medium magnetic product. This will reduce the cost of the finished concentrate by reducing the number of mills of the third stage.

To improve the quality of the concentrate in comparison with the prototype, a magnetic and richer product must be crushed and enriched in two separate stages to obtain a high-quality concentrate (dependent claim 3 of the invention, Fig. 4).

The medium-magnetic and poorer product contains mainly poor intergrowths of magnetite with host rocks. With magnetic enrichment of the mid-magnetic product crushed in the second stage, the magnetic separator will have few magnetic grains in the feed of the magnetic separator, and they will contribute to a lesser extent to the transfer of part of the rock grains to the magnetic product due to the ingress of rock particles into magnetite flocs. This will lead to a more complete withdrawal of waste rock particles into the tails. For the complete withdrawal of waste rock particles into the tails and for obtaining a concentrate from a medium magnetic product with a quality comparable to the concentrate quality obtained by the enrichment method of the prototype, it is necessary to subsequently grind the medium magnetic product in two stages and enrich it sequentially using wet magnetic separation (Fig. 2 )

Improving the quality of iron concentrate or reducing the cost of concentrate is achieved by using a combination of essential features characterizing the proposed enrichment method. In the patent and scientific and technical literature, the totality of the above features of the method of enrichment of iron ore is not found.

In the drawings of FIG. 2-4, variants of technological schemes for implementing the method are shown.

In all schemes (Fig. 2-4) shows the implementation of the first stage of grinding in an open grinding cycle. It is possible to use a closed grinding cycle implemented with a ball mill and classifier in the first grinding stage. The implementation of the second and third stages of grinding in a closed cycle is possible according to various schemes, for example using combined preliminary and calibration classification, or using calibration classification, or using another scheme. In addition, in a closed loop, the wet magnetic separation operation (between the mill and hydrocyclones) can be used. In this case, the discharge of the mill is fed to a magnetic separator. The magnetic product of the separator is sent for classification in hydrocyclones. The use of the wet magnetic separation operation (MMS-II) in a closed cycle of the second stages of grinding is shown in all schemes (Fig. 2-4). All schemes (Fig. 2-4) show the implementation of the ore beneficiation process without de-slamming operations. If the ore being processed during grinding is prone to sludge formation (like ferruginous quartzites), then the discharge of hydrocyclones of the operations of the classification of the second and third stages of grinding before wet magnetic separation (operations MMC-III and MMC-IV) is subjected to deslamination. All schemes (Fig. 2-4) show the implementation of the wet magnetic separation stage in one operation (in one go). In many enrichment plants, in one stage of enrichment, several sequential MMC operations are used (several techniques). The implementation of the individual stages of grinding, the use of additional operations and their number in a particular stage of grinding and concentration depends on the type and properties of iron ore [3, 4]. This does not affect the set of essential features characterizing the proposed method of enrichment.

The method of beneficiation of iron ores according to claim 1 is as follows (Fig. 2).

The initial iron-containing ore is ground in the first stage, for example, in an open cycle in a mill, for example, of MSC type, after which the ground ore is enriched in the first stage of wet magnetic separation by means of a wet magnetic separator, for example, of PBM type, to obtain an intermediate product of the first stage of wet magnetic separation and dump tailings. The intermediate product of the first stage of wet magnetic separation is fed to wet magnetic gravity separation (MMS-G) and divided according to magnetic properties into magnetic and medium magnetic products, for example, by means of a drum magnetic gravity separator with an increased bath depth [5], consisting of a loading device, non-magnetic rotating drum, inside which a fixed magnetic system is installed, creating a magnetic field on the surface of the drum, placed in a bath with a slot for unloading the medium magnetic product and from the tray for unloading the magnetic product. The distance between the working surface of the drum and the bottom of the bath is, for example, 0.1-0.15 m, which provides a value of magnetic induction at the bottom of the bath, for example, 0.005 T. As a result of increasing the distance between the working surface of the drum and the bottom of the bath, the depth of the pulp stream increases and the speed of the pulp decreases, which contributes to a faster deposition of separated particles on the bottom of the bath. The depth of the bath is chosen so that the medium-magnetic particles are not attracted to the separator drum, and the magnetic particles are attracted. To do this, use the dependence of reducing the induction of the magnetic field of the separator with increasing distance from the surface of the drum, for example, shown in FIG. 5. Magnetic induction at the bottom of the bath of the separator should provide a magnetic force sufficient to extract magnetic particles and insufficient to remove medium-magnetic particles. The depth of the bath is selected based on the magnetic properties and size of the intermediate product of the MMC-I operation and on the expected ratio of magnetic and medium magnetic products. Other apparatus designs can be used to separate MMC-I intermediate product into magnetic and medium magnetic.

The medium-magnetic product of a drum magnetic gravity separator with an increased bath depth is crushed in the second grinding stage, consisting of a mill of the MShTs type, magnetic separators of the PBM type and hydrocyclones of the HZ type, operating in a closed cycle with the mill of the MShTs type. The medium magnetic product is fed to the mill of the second stage of the MSHC type. The unloading of the mill of the MSHC type of the second stage is fed to the magnetic separators PBM and get the intermediate product of the second stage of wet magnetic separation and dump tailings. The intermediate product of the second stage of wet magnetic separation is fed into hydrocyclones of the GZ type to obtain sands, which are sent back to the mill of the MSC type of the second stage, and the discharge, which is the final product of the second grinding stage. The medium magnetic product crushed in the second stage (discharge of the second stage hydrocyclones) is enriched in the third stage of wet magnetic separation by means of a wet magnetic separator of the PBM type to obtain rich industrial product and tailings. Rich industrial product is ground in the third stage of grinding, consisting of a mill type MSHTs and hydrocyclones type HZ working in a closed cycle with a mill type MShTs. Rich industrial product is fed to HC-type hydrocyclones to produce sands, which are sent to a mill of the MSHC type of the third stage, and plum, which is the final product of the third grinding stage. The unloading of the mill of the MSC type of the third stage is fed back to the hydrocyclones of the GC type of the third stage of grinding. The rich industrial product ground in the third stage is enriched in the fourth stage of wet magnetic separation by means of a wet magnetic separator of the PBM type to obtain concentrate and tailings.

The magnetic product is processed according to various schemes, depending on the tasks solved by the invention in accordance with paragraphs. 2-3 claims (Figs. 3-4).

The method according to p. 2 is as follows (Fig. 3).

The magnetic product is ground in a separate second grinding stage, consisting of a mill type MSHTs, magnetic separators like PBM and hydrocyclones type HZ working in a closed cycle with a mill type MShTs. The magnetic product is fed to the mill of a separate second stage of the MSHC type. The unloading of the mill of the MSHC type of a separate second stage is fed to the magnetic separators PBM and get the intermediate product of a separate second stage of wet magnetic separation and dump tailings. The intermediate product of a separate second stage of wet magnetic separation is fed into hydrocyclones of the GZ type to obtain sands, which are sent back to the mill of the MSC type of a separate second stage, and the discharge, which is the final product of a separate second grinding stage. The magnetic product ground in a separate second stage is enriched in a separate third stage of wet magnetic separation by means of a wet magnetic separator of the PBM type to produce a second concentrate and tailings.

The method according to p. 3 is as follows (Fig. 4).

The second concentrate is ground in a separate third stage of grinding, consisting of a mill type MSHTs and hydrocyclones type HZ working in a closed cycle with a mill type MShTs. The second concentrate is fed into HC-type hydrocyclones to produce sands, which are sent to a mill of the MSHC type of a separate third stage, and a discharge, which is the final product of a separate third grinding stage. The unloading of the mill of the MSC type of a separate third stage is fed back to the hydrocyclones of the GC type of a separate third stage of grinding. The second concentrate ground in a separate third stage is enriched in a separate fourth stage of wet magnetic separation by means of a wet magnetic separator of the PBM type to produce high-quality concentrate and tailings.

An experimental verification of the proposed method was performed in laboratory conditions for titanomagnetite ore. Comparative indicators of enrichment for the proposed method and for the prototype are given in table. 2. The results of the experiments showed that the use of the proposed method allows, in comparison with the prototype, to increase the iron content in the total concentrate by 3.29% while maintaining the volume of grinding equipment (dependent claim 3 of the claims) or by 0.68% with a decrease in the volume of mills of the third stage twice (dependent paragraph 2 of the claims). The method according to claim 3 allows, as one of the concentrates, to obtain a high-quality concentrate with an iron content of 66.6%.

An example implementation of the method of beneficiation of iron ores according to claim 1 as applied to titanomagnetite ore (Fig. 2)

The initial ore with an iron content of 15.6% is crushed in the first stage grinding in an open cycle in a core mill MSC-3600 × 4500 to a particle size of 18.7% class - 0.071 mm and fed into magnetic separators PBM-150/200 of the first stage of magnetic separation with obtaining an intermediate product with an iron content of 22.3% and tailings with an iron content of 6.0%. The intermediate product of the first stage of wet magnetic separation is fed to a magnetic gravity separator (upgraded PBM-150/200 separator with increased bath depth) to produce a magnetic product with an iron content of 39.1% and an average magnetic product with an iron content of 12.89%. The medium magnetic product is crushed in the second grinding stage, consisting of the mill MSHTs-3600 × 4500, wet magnetic separators PBM-P-150/200 and hydrocyclones HZ-710, operating in a closed cycle with the mill MShTs-3600 × 4500, with the discharge of hydrocyclones HZ -710 with a fineness of 76.16% of the class -0.071 mm and an iron content of 52.7% and tailings of separators PBM-P-150/200 with an iron content of 5.71%. The discharge of hydrocyclones of the second grinding stage is fed to the third stage of wet magnetic separation in the separators PBM-PP-150/200 to obtain a rich intermediate product with an iron content of 59.4% and tailings with an iron content of 6.2%. Rich industrial product is crushed in the third grinding stage, consisting of mill MSHTs-3600 × 4500 and hydrocyclones GTs-500, operating in a closed cycle with mill MShTs-3600 × 4500, with the discharge of hydrocyclones GTs-500 with a particle size of 99% of class -0.071 mm and the iron content of 59.4%. The discharge of hydrocyclones of the third grinding stage is fed to the fourth stage of wet magnetic separation in the separators PBM-PP-150/200 to obtain a concentrate with an iron content of 63.2% and tailings with an iron content of 6.9%.

An example implementation of the method according to p. 2 (Fig. 3) in relation to titanomagnetite ore

The magnetic product is ground in a separate second grinding stage, consisting of the mill MSHTs-3600 × 4500, wet magnetic separators PBM-P-150/200 and hydrocyclones HZ-710, operating in a closed cycle with the mill MSHTs-3600 × 4500, to obtain a discharge of hydrocyclones GC-710 with a particle size of 75.4% of the class -0.071 mm and an iron content of 57.1% and tailings of separators PBM-P-150/200 with an iron content of 5.96%. The discharge of hydrocyclones of a separate second stage of grinding is fed to a separate third stage of wet magnetic separation in separators PBM-PP-150/200 to obtain a second concentrate with an iron content of 62.9% and tailings with an iron content of 6.25%. The total concentrate, consisting of a concentrate obtained from a medium magnetic product and a second concentrate, contains 62.98% of iron.

An example implementation of the method according to p. 3 (Fig. 4) in relation to titanomagnetite ore

The second concentrate is crushed in a separate third grinding stage, consisting of mill MSHTs-3600 × 4500 and hydrocyclones GTs-500, working in a closed cycle with mill MShTs-3600 × 4500, to obtain a discharge of hydrocyclones GTs-500 with a particle size of 99.5% of class 0.071 mm and an iron content of 62.9%. The discharge of hydrocyclones of a separate third stage of grinding is fed to the fourth separate stage of wet magnetic separation in separators PBM-PP-150/200 to obtain a high-quality concentrate with an iron content of 66.6% and tailings with an iron content of 28.68%. The total concentrate, consisting of a concentrate obtained from a medium magnetic product and a high-quality concentrate, contains 65.59% of iron.

Implementation of the proposed method in comparison with the prototype allows, due to the separation according to the magnetic properties of the intermediate product after the first grinding stage, to increase the iron content in the total concentrate by 3.29% while maintaining the volume of grinding equipment or by 0.68% with a decrease in the volume of grinding equipment. It is possible, as one of the concentrates, to obtain high-quality concentrate with an iron content of 66.6%, respectively.

Information sources

1. Patent No. 2366511 of the Russian Federation, MCP B03B 7/00, B03C 1/00. The method of concentration of iron ores / V.V. Karmazin, N.G. Sinelnikova, I.V. Palin, T.N. Gzogyan. No. 2008114625; declared 04/17/08; publ. 09/10/09. Bull. Number 25. - 3 p.: Ill.

2. Patent No. 2365421 of the Russian Federation, MKP V03C 1/247. Magnetic separator / S.I. Kretov, V.V. Karmazin, I.V. Palin, N.G. Sinelnikova, Yu.M. Pozharsky. No. 2008114626/03; declared 04/17/08; publ. 08/27/09. Bull. No. 11. - 2 p.

3. Ostapenko P.E. Theory and practice of iron ore beneficiation. M .: Nedra, 1985.S. 161-177.

4. Handbook of ore dressing. Processing plants / Under. ed. O.S. Bogdanova, Yu.F. Nenarokomova. 2nd ed., Revised. and add. M .: Nedra, 1984.358 s.

5. Patent No. 2492933 of the Russian Federation, IPC V03C 1/10. The magnetic separation method and device for its implementation / Pelevin A.E., Sytykh N.A., Mushketov Ant. Andes. - No. 2010153922/03; declared 12/27/2010; publ. 09/20/2013, bull. No. 26.

Claims (3)

1. The method of beneficiation of iron ores, including several stages of grinding, wet magnetic separation of the crushed products of each stage to obtain intermediate products and tailings and to obtain concentrate using wet magnetic separation after the last grinding stage, characterized in that the intermediate after the first grinding stage is separated by magnetic properties to obtain magnetic and medium magnetic products, the medium magnetic product is crushed and enriched using wet magnetic separation in n how many stages to obtain final tailings and concentrate after the final grinding step. 2. The method according to p. 1, characterized in that the magnetic product is ground in a separate second stage and enriched by wet magnetic separation to obtain a second concentrate and tailings. 3. The method according to p. 2, characterized in that the second concentrate is ground in a separate third stage and enriched using wet magnetic separation to obtain high-quality concentrate and tailings.

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