WO2009077425A1

WO2009077425A1 - Method for producing building material from steel slag

Info

Publication number: WO2009077425A1
Application number: PCT/EP2008/067335
Authority: WO
Inventors: Andreas Jungmann
Original assignee: Cala Aufbereitungstechnik Gmbh & Co. Kg
Priority date: 2007-12-18
Filing date: 2008-12-11
Publication date: 2009-06-25

Abstract

The invention relates to a method for working up steel slag for producing building material, in which primary metallurgy slag, occurring in primary metallurgy, is at least predominantly granulated and ground in a dry state in a dry grinding stage, secondary metallurgy slag, occurring in secondary metallurgy, is ground in a second grinding stage, and, in each case after metal separation has taken place, the primary metallurgy slag and secondary metallurgy slag products produced in such a way are added to a building product to produce concrete products, and the invention relates to a building material produced by the method. In the case of the method according to the invention for producing building material on the basis of steel slag, in particular high-grade steel slag, two slag fractions are brought together, at least one slag fraction of these two (the primary metallurgy slag) being hydraulically active.

Description

METHOD FOR BUILDING MATERIAL FROM STEEL SLAG

The invention relates to a process for the treatment of steel slag for the production of building materials, in which primary metallurgical slag produced in primary metallurgy is at least predominantly used

Part granulated and dry ground in a dry grinding stage, in the secondary metallurgy secondary metallurgy slag is ground in a second grinding stage and the thus produced primary metallurgical slag and secondary metallurgical slag products after each metal separation one

Building material for the production of concrete products are added. Furthermore, the present invention relates to a building material for the production of concrete products containing a first and at least one further building material, wherein the first building material from a primary metallurgy slag product and the further building material consists of a secondary metallurgical slag product, which according to are prepared according to the invention.

Steel slags are produced in the production of alloyed and unalloyed steels, which are generally produced in two stages by melting in the electric furnace operation (primary metallurgy) as well as in converter operation and the

Pfannenmetallurgie (secondary metallurgy) are produced. In which The above-mentioned manufacturing processes are different slags due to the two-stage process. After separation from the metallurgical process, cooling of the so-called primary metallurgical slag is carried out in buckets. As a result of the further casting technology processing of the stainless steel melt produced in electric furnace and converter operation, the casting of the stainless steel melt results in the formation of a so-called secondary or ladle metallurgical slag. Depending on the composition, slags are generated, most of which break down finely.

The chemical composition of the slag species varies somewhat depending on the aggregates, but can be characterized essentially as follows:

Comparison of blastfurnace slag (HS), Linz-Donawitz process (LD), electric (EAF) and converter (AOD) / ladle metallurgy slag:

H. ingredient HS LD EAF AOD / pan

SiO ₂ 35, 6 14.5 22, 1 19.0

Al ₂ O ₃ 1 1, 8 2.5 4.3 10.8

CaO 40.2 49.5 47, 1 50.3 MgO 9.5 2.5 6.8 7.8

Fe ₂ O ₃ 0.8 23, 5 4.8 6.4

CaO / SiO ₂ 1, 13 3, 4 2, 13 2.65 (basicity)

CaO + MgO / SiO ₂ 1, 4 3, 6 2.44 3, 02 (extended basicity)

In the first approximation, the higher the basicity, the greater the probability that space utilization will not be achieved during utilization.

Differences are mainly to be found in the composition of the primary and secondary metallurgical slag; the composition of secondary metallurgical slag varies more in composition than any other type.

At present, slag recycling is predominantly used as landfill or road construction.

Much of the volume is dumped after recovery of the metal contents.

After separation from the metallurgical process, the slag is usually slowly cooled in pails or poured into beds; furthermore, a careful spraying with water usually takes place, which serves for the final cooling as well as the dust precipitation.

The metal recovery methods used are dry processes, which are typically fracturing, screening, magnetic separation and hand-picking. Recently, efforts have been made to use sensor sorting techniques, which may be termed automated picking. These recognize, for example, by means of inductive sensors metals and eject them by means of compressed air. Wet processes through a combination of selective comminution in crushers and rod and ball mills release the metal content, which can not be crushed due to its ductility. These shares are then recovered by classification. This procedure sometimes combines a multi-stage density separation as well as the use of wet magnetic separators.

In the optimal design of the wet process, it is possible to achieve recovery rates of the metal contents of well over 90% for the grain size> 0.063 mm. Disadvantage of this method is that a slag product is formed, which results in almost 100% less than 0.2 mm with proportions of> 80% below 0.063 mm. Such a product is currently regularly dumped in Europe, mainly due to the remaining and elutable heavy metal contents. Attempts to recover the metal contents as early as possible from coarser grains in order to produce higher proportions of lumpy material, resulting in significant losses of metal. Nevertheless, it has been shown that in this way, however, a lumpy aggregate can be produced, which can be used hydraulically bound in road construction with appropriate pre- and post-treatment structurally and also from an environmental point of view. However, sometimes contained therein proportions of CaO and especially MgO, which are known to affect the space stability. It is undisputed that the risk of this deterioration increases with increasing grain size, since, especially in the coarser grains, the reactions by the oxides of the alkalis-above all MgO-occur with considerable time delay. The finer the product, the less time-delayed this reaction occurs.

Moreover, it has hitherto been necessary to hydraulically bond the additive obtained by the wet process to add large amounts of cement to the aggregate as a hydraulically active ingredient. The associated costs are considerable, so that a Use of the cement / slag mixture as a building material so far no actually widespread has found.

It is possible to vitrify slags from the pig iron production in the blast furnace by granulation. The resulting "slag tenders" have a ground hydraulic properties and are therefore also used in the production of blastfurnace cements, whose use is now accepted and certified worldwide and, of course, hydraulics are only given when the sands are dry ground.

It is also known that LD slags were also experimentally granulated. It should be noted that this was done in the dry process.

The invention is based on the object of proposing a method which makes the use of steel slag, in particular stainless steel slag, appear attractive as a building material on an industrial scale.

This object is achieved by a method having the features of claim 1 and a building material having the features of claim 8.

In the process according to the invention for the production of building materials based on steel slag, two slag components are combined, of which at least one slag component is hydraulically active, that is to say that it is comparable with cement in its setting action. A second portion of slag can be ground dry or with the addition of water, ie in a wet process, preferably for producing a fine grain, ie <0.2 mm.

With regard to an industrial use on an industrial scale, the method is particularly advantageous executable when the primary metallurgical slag and the secondary metallurgical slag of the same Derived from melt, so the process in the immediate continuation of a kiln line in the processes of a steel plant can be integrated.

Preferably, the proportion of the primary metallurgy slag fed to the dry grinding stage is formed from an upper volume fraction of a slag volume arranged in a slag container for receiving the primary metallurgical slag and the volume fraction of the primary metallurgical slag supplied to the second grinding stage from a lower volume fraction of the slag volume. This ensures that, due to a gravity separation of metal fractions in the slag container, the primary metallurgical slag content supplied to the dry grinding stage has comparatively little metal content.

A smaller proportion of the primary metallurgical slag removed from the lower volume fraction can preferably be combined with the secondary metallurgical slag without prior granulation and fed therewith to the second grinding stage.

In particular, it has been found to be advantageous if 51 to 80% of the primary metallurgical slag of the dry grinding stage and the remainder of the remainder of the second grinding stage are supplied.

If the granulation of the primary metallurgy slag fraction takes place with supply of cooling gas, the granulation can be significantly accelerated.

By adding additives, such as sand, the properties of the granules can be influenced. By adding substances which influence the viscosity of the slag, it can be achieved, for example, that existing residual metal fractions deposit more easily or more quickly at the bottom of the slag vessel. In the method according to the invention for the production of building materials based on steel slag, two slag components are combined, of which a slag component is hydraulically active, ie cementable in its setting effect, and a second slag component dry or with the addition of water, ie in a wet process of comminution preferably for producing a fine grain, ie <about 0.2 mm, is treated. In the case of the second grinding carried out dry, it is possible to dispense with an optionally previously carried out granulation.

Accordingly, in one embodiment of the invention

A method for producing the hydraulically active slag component is a cooling of the first formed as a primary metallurgical slag slag portion for producing a granulate and subsequent comminution of the granules for producing a hydraulically active grain mass in a dry process carried out, is comminuted for crushing the slag content preferably in a grinding process, This means that this first slag fraction serves as a quasi-cement substitute.To produce the second slag fraction, preference is given to secondary metallurgical slag which is either dry-shredded or also comminuted in a wet process.

In particular, when the cooling gas is air, a particularly fine granulation can be achieved by a corresponding oversupply of oxygen.

In particular, if the slag is not slag of a high-grade steel melt, there may be a deficit of sand in the melt or slag, so that it may be advantageous to use a granulated aggregate, in particular sand, the melt or granulation Add the intended primary slag content. The building material according to the invention for the production of concrete products has the features of claim 1 1.

According to the invention, the building material contains a first and at least one further component of building material, wherein the first component of building material consists of a primary metallurgical slag product and the further component of building material consists of a secondary metallurgical slag product produced according to a method according to one of claims 1 to 10 are.

Particularly advantageous for the desired effect that the building material must have no or only a very small proportion of cement in order to be used for the production of concrete products, when the primary metallurgical slag product and the secondary metallurgical slag product in a ratio between 1: 1, 5 and 1: 4 are present.

It is particularly preferable for the building material to have the primary metallurgical slag product and the secondary metallurgical slag product in a ratio of between 1: 1, 8 and 1: 2.4.

The building material according to the invention can be used in an embodiment particularly advantageous for the production of ready-mixed concrete. In addition, a use of the building material for the production of concrete components, in particular prefabricated components, proves to be advantageous. In particular in road construction and road construction, the use of the building material according to the invention for the production of concrete blocks is advantageous, in which case the use for the production of paving stones is particularly noteworthy, since here due to the building material according to the invention usually contained in conventional paving stones shares of binders and fillers, especially on fly ash and cement, can be significantly reduced or almost replaced, whereby the manufacturing cost of paving stones can be reduced accordingly in the result. In this case, a building material composition has proven to be particularly advantageous for such a paving stone proven in which the fly ash fraction to 100% and the usually existing cement content to about 2/3 are replaced by the use of the building material according to the invention.

In principle, it is also possible to use secondary metallurgical slag to form the hydraulically active component and to use the primary metallurgical slag to form the "wet" component However, the reverse choice of components proves to be particularly advantageous as the secondary metallurgical slag regularly becomes larger alkaline Having proportions as the primary metallurgical slag and so by the treatment of the secondary metallurgy slag in the wet process for increased space stability of the grain with the therein contained proportions of CaO and MgO to provide.

Although the chemistry of steel slags and blastfurnace slag differ, it is still technically possible to produce a largely / partially glassy product by suitable cooling methods for stainless steel slags. Such a product develops - as well as the Hüttenzement - in the dry ground state hydraulic / binding properties.

Slag from the conventional process of slag cooling has on average about the following grain distributions:

mm Primary metallurgical slag Secondary metallurgical slag

+20 50 - 65% 8 - 15%

2 - 20 10 - 15% 10 - 15%

0, 1 - 2 5 - 10% 20 - 25%

-0, 1 15 - 20% 55 - 65% As a so-called decomposition slag, the slag of the secondary metallurgy is usually referred to as it "post-shreds" in the further course of deposition due to the chemical reactions in the strongly basic product.The ratio of the two slag proportions is in the first approximation and with certain deviations 50:50 ,

The primary metallurgical slag can now be glazed by sudden cooling and does not tend to decay. In addition, a composition is given that promises hydraulicity.

In a sudden cooling with simultaneous oversupply of oxygen, all components of the slag oxidize and are finely dispersed in the granulation product. So you can either perform the granulation waiving oxygen - economically and technically rather unrealistic - or treat the primary metallurgical slag as follows:

The primary metallurgical slag is tipped out of the pails in 2 phases:

1 . ... an amount of about 70%, because the metal fraction has accumulated in the lower area of the tub. This slag content is tilted under air addition and thereby granulated, since this proportion is virtually metal-free.

2. ... an amount of about 30%, which is tilted conventionally, whereby the metallic fraction is retained.

The secondary metallurgical slag is conventionally cooled. This results in a bulk split of about 30-35% vitrified primary slag and 65-70% conventionally cooled secondary dross.

The glazed portion is fed to a dry grinding; the conventionally cooled slag enters the wet grinding process. From the dry-ground slag, a hydraulically active product is produced, which serves as a cement substitute (Blaine values> 3000 cnrVg), in order to bind the wet-finely shredded residual slags in the concrete technical processing. As a result, environmentally relevant pollutants are safely integrated with significantly reduced addition of regular cement. This leads to a considerable cost savings. The technical concrete utilization is, for example, the production of artificial aggregate or the production of sand-rich concretes. A replacement of up to 75% of the usual regular binder is possible.

Starting from the exemplary quantitative distribution given above, the further processing of the primary metallurgical slag and the secondary metallurgical slag can take place as illustrated by way of example with reference to the drawing figure, wherein 1/3 of the slag (primary metallurgical slag) is subjected to dry grinding and 2/3 the slag (namely the secondary metallurgical slag) is wet milled with the high content of ultrafine grain. In the drawing figure with SECS the secondary metallurgical slag (from the converter operation and the ladle furnace), with GEAFS the dry ground electric furnace slag and with SFA the hard coal fly ash are called. The metal recycling processes used in wet processing are the known systems; In the dry processing, a density separation process in a fluidized fluidized bed, possibly in combination with a high-pressure dry separation, can be used in the circulation with the screening process for cement flour separation. If the second grinding is also dry grinding, metal recovery processes in a fluidized fluidized bed in conjunction with magnetic separation can also be used.

The entire procedure is as follows:

The slags - no matter how they were cooled - are wet for further processing due to the regular environmental conditions. From the glazed slags, the portion which is glazed is screened out by a simple wet sieving. Through the glazing, a fraction is selectively obtained, which is in the mid-grain range, ie between 1, 5 and 8 mm. (Fraction boundaries are chosen as examples!)

Fractions above 8 and below 1, 5 mm are not or only to a limited extent fed to the processing by the dry grinding.

The slag not supplied to the glazing enter the wet grinding or the second dry grinding.

The products of the two parallel systems are:

• Metal from wet grinding or second dry milling> 90% metal content

• Metal from dry grinding,> 90% metal content

• Dewatered slag 0 - 0.2 mm from the wet grinding

• Cement powder from dry grinding,> 3000 cnrVg

In summary, it can be stated that the illustrated method for the treatment and utilization of stainless steel slag by the inventive combination of first dry and second dry or wet treatment of the slag on the one hand allows the production of a hydraulically active product based on the dry-processed stainless steel slag content and also due to the dry processing a Increasing the output of metal from the slag allows. The essential steps of the process for producing a building material based on a steel slag are:

Dry granulation of about 30-35% of the slag,

Dry processing of the dry granulated slag (30-35%),

• second dry or wet treatment of the 65 - 70% of the slag fraction and Hydraulic utilization of finely ground slags based on the production of sand-rich concretes.

Claims

claims

1 . Process for the treatment of steel slag for the production of building materials, in which primary metallurgy slag produced in primary metallurgy is at least predominantly granulated and dry ground in a dry grinding stage, secondary metallurgy slag produced in secondary metallurgy is ground in a second grinding stage, and thus produced primary metallurgical slag and secondary metallurgical slag products after each metal separation one

Building material for the production of concrete products are added.

2. The method according to claim 1, characterized in that the second grinding stage is carried out as a dry grinding stage.

3. The method according to claim 1, characterized in that the second grinding stage is carried out as a wet grinding stage.

4. The method according to any one of the preceding claims, characterized in that the primary metallurgical slag and the secondary metallurgical slag originate from the same melt.

5. The method according to any one of the preceding claims, characterized in that the dry grinding stage supplied proportion of primary metallurgical slag from an upper volume fraction of slag contained in a slag tank for receiving the primary metallurgical slag and the second grinding stage supplied volume fraction of the primary metallurgical slag a lower volume fraction of the slag volume is formed.

6. The method according to any one of the preceding claims, characterized in that a smaller proportion of the primary metallurgical slag is brought together without prior granulation with the Sekundärmetallurgieschlacke and supplied with this the second grinding stage.

7. The method according to any one of the preceding claims, characterized in that 5 1 to 80% of the primary metallurgical slag of the dry grinding stage and the remainder are supplied for the greater part of the second grinding stage.

8. The method according to any one of the preceding claims, characterized in that the granulation of the primary metallurgy slag fraction under

Supply of cooling gas, preferably air takes place.

9. The method according to any one of the preceding claims, characterized in that the melt or the primary metallurgy slag fraction prior to granulation, a granulated aggregate, preferably sand, is added.

10. The method according to any one of the preceding claims, characterized in that the melt or the primary metallurgy slag fraction before slagging the slag additives are added to influence the viscosity of the slag

1 1. Building material for the production of concrete products comprising a first and at least one further building material content, wherein the first building material content of a primary metallurgical slag product and the further building material content consists of a secondary metallurgical slag product, which according to the method of any one of claims

1 to 10 are made.

12. A building material according to claim 1 1, characterized in that the building material, the primary metallurgical slag product and the secondary metallurgical slag product in a ratio of

1: 1, 5 to 1: 4.

13. The building material of claim 1 1, characterized in that the building material, the primary metallurgical slag product and the secondary metallurgical slag product in a ratio of

1: 1, 8 to 1: 2.4.

14. Building material according to one of claims 1 1 to 13 characterized by the use for the production of ready-mixed concrete.

15. Building material according to one of claims 1 1 to 13 characterized by the use for the production of concrete components.

16. Building material according to one of claims 1 1 to 13 characterized by the use for the production of concrete blocks.

17. Building material according to one of claims 1 1 to 13 characterized by the use for the production of paving stones.