steel slag ball mill in belgium

slag mill

slag mill

Slag ball mill is a kind of equipment used to grind the slag into powder particles. The technical that uses the tube mill on the production of slag has been very mature. The slag produced can be used as concrete admixture, reducing the project costs significantly and enhanced the compressive strength, tensile strength, shear strength and bending strength of the concrete. Product characteristics: 1. Return on investment is high The widely use of slag increases the market demand to slag gradually. In recent years, investment in slag production line has been a new favorite in investment market. One production line can recover the cost in 1-3years. 2. Improving the quality of final product effectively. 3. With more than 40-year experience on slag mill manufacture, we have strong technical strength. Working principle: The energy saving ball mill is a horizontal cylindrical rotating device, which has two cabins. It is energy saving grate ball mill and the outside runs along the gear. The materials enter the first cabin of the mill spirally and evenly through the feeding apparatus and hollow shaft. In the first cabin, there is stepped liner or corrugated liner, and steel balls with different specifications. The centrifugal force generating from the rotation of the cylinder brings steel balls to a certain height, and then the balls fall, thumping and grinding the materials. After coarse grinding in the first cabin, the materials enter the second cabin by single-wall partition. There is flat liner and steel balls in the second cabin, where the materials are grinded further. Finally, the powder is discharged through discharge grate and the grinding operation is finished. Structure characteristics: The ball mill mainly consists of feeding part, discharging part, rotary part, drive (reducer, small driving gear, motor, electronic control) etc. The hollow shaft adopts steel castings and the lining can be replaced. The rotary gear is processed with casting hobbing. There is wear-resistant liner in the cylinder and have strong wear resistance. The machine runs stably and has reliable performance.

Slag ball mill is a kind of equipment used to grind the slag into powder particles. The technical that uses the tube mill on the production of slag has been very mature. The slag produced can be used as concrete admixture, reducing the project costs significantly and enhanced the compressive strength, tensile strength, shear strength and bending strength of the concrete.

The widely use of slag increases the market demand to slag gradually. In recent years, investment in slag production line has been a new favorite in investment market. One production line can recover the cost in 1-3years.

The energy saving ball mill is a horizontal cylindrical rotating device, which has two cabins. It is energy saving grate ball mill and the outside runs along the gear. The materials enter the first cabin of the mill spirally and evenly through the feeding apparatus and hollow shaft. In the first cabin, there is stepped liner or corrugated liner, and steel balls with different specifications. The centrifugal force generating from the rotation of the cylinder brings steel balls to a certain height, and then the balls fall, thumping and grinding the materials. After coarse grinding in the first cabin, the materials enter the second cabin by single-wall partition. There is flat liner and steel balls in the second cabin, where the materials are grinded further. Finally, the powder is discharged through discharge grate and the grinding operation is finished.

The ball mill mainly consists of feeding part, discharging part, rotary part, drive (reducer, small driving gear, motor, electronic control) etc. The hollow shaft adopts steel castings and the lining can be replaced. The rotary gear is processed with casting hobbing. There is wear-resistant liner in the cylinder and have strong wear resistance. The machine runs stably and has reliable performance.

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energy saving ball mill|cone ball mill|tube ball mill|cement mill|dry magnetic separator

energy saving ball mill|cone ball mill|tube ball mill|cement mill|dry magnetic separator

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ball mill forraking out the slag ball mill and separating

ball mill forraking out the slag ball mill and separating

Our ball mill can grind ore or other materials that can be grinded either by wet process or by dry process. The ball mill is suitable for the beneficiation and grinding of fly ash, limestone, quartz sand, aluminium powder, coal powder, steel slag, ore, potassium feldspar, iron ore, iron slag, aluminium slag, silicon carbide, alumina, coal gangue and other materials.

Ball mills tumble iron or steel balls with the ore. . In general, ball mills can be operated either wet or dry and are capable of producing products in the order of. Contact US dry grinding ball mill process flow diagram R4H. Dry and wet grinding common Ball mill ...

vertical mill is integrated with tertiary crushing, drying, grinding, powder separation and conveying and is the best choice for processing slag and cement. Then compared with ball mill, what are the advantages of vertical mill. 1. High powder grinding

Cement mill - Wikipedia 2019-10-18 A cement mill (or finish mill in North American usage) is the equipment used to grind the hard, nodular clinker from the cement kiln into the fine grey powder that is cement Most cement is currently ground in ball mills and also.

Germany-based Tomra Sorting Recycling, part of Norway's Tomra Group, tried a new platform in June to launch new products and technology it otherwise would have exhibited at major trade fairs. On June 9, the company hosted its "Symphony of all Sorts" online event, which served in part to introduce ways in which its AutoSort, SpeedAir, SharpEye, Deep Learning, FlyingBeam and CyBot join ...

The energy saving ball mill is a horizontal cylindrical rotating device, which has two cabins. It is energy saving grate ball mill and the outside runs along the gear. The materials enter the first cabin of the mill spirally and evenly through the feeding apparatus and

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The invention relates to a steel-slag processing method, including the procedures of separation, magnetic separation, fine crushing, magnetic separation, ball-mill washing, etc. The slag and steel are separated by fine processing of waste steel slag, the iron content ...

Ball Mill Forraking Out The Slag Ball Mill And Separating. Efficiency of Ball Mills vs. Roller Mills - bulk-onlineNov 14, 2011 Efficiency of Ball Mills vs. Roller Mills If this is your first visit, be sure to check out the FAQ by clicking the link above.

belgium ball mill for slag grinding Know More 2nd hand 125hp 20 ton ball mill sa 300 tpd slag grinding ball mill electric load 40tph ball mill in a rotating ball mill The granulated slag after drying Ball millWikipedia Grinding can be carried out either wet or dry Aside from ...

vertical mill is integrated with tertiary crushing, drying, grinding, powder separation and conveying and is the best choice for processing slag and cement. Then compared with ball mill, what are the advantages of vertical mill. 1. High powder grinding

Seperating Ball Mills From Palm Kernal Nut Processing capacity:131-468t/h Feeding size:11mm Appliable Materials: new-type building material,fertilizer,iron ore,ore,construction rubbish,glass etc.All grindable materials, various metal ores, non-metallic ores, non

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Ball Mill,Griding Mill,Raymond Mill Pictures-Yuanhua Ball Mill Picture.This page is bout the Ball Mill and grinding plant pictures,if you want to know more info about the Ball Mill,or the pictures,you can find on .

Ball mill - Flotation machine A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting Milling also refers to the process of breaking down, separating, sizing, . Rod mills are less common than ball mills for grinding minerals.

At this point, the particle size of slag is mostly <5mm. With the use of the ball mill, the granular slag can be processed into ultrafine slag powder. The focus is to enhance the grinding function of the ball mill. Firstly, adjust the position of the separating board of

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Ball mill - Flotation machine A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting Milling also refers to the process of breaking down, separating, sizing, . Rod mills are less common than ball mills for grinding minerals.

Gold Ore Ball Mill for Grinding Stone Gold ore ball mill for grinding stone Ball mill is the key re-crush eqipment after the crushing. Ball mill is widely used in cement silicate products new building materials refractories chemical fertilizer black and non-ferrous metal ore-dressing as well as the production industry of glass or ceramics

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At present, the slag powder grinded by ball mill and classified by separator is widely used in the production process flow system. It plays an important role in the fine grinding. Ball through the transformation, unique screening device and grate holes arranged in the form of changes to adapt to different requirements than the surface area of slag powder.

slag material grinding ball mill - esterzwinkels Steel Slag Grinding Machine. Steel Slag Grinding Machine Ball mill is successfully made use of for polishing Crushing grinding mixing of various different types of products Separated iron particles from magnetic separator which is not 100 pure metal because few sand particles are still attached with iron particles due to rusted material

Dry Type Industrial Ball Mill For Furnace Slag Grinding For India Steel Plant. blast furnace slag drying for milling in a ball mill. 2020-8-19 blast furnace slag drying for milling in a ball mill. HLM Series vertical roller mill is a kind of advanced mill developed by Hongcheng based on two decades of RD experience and introduction of

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ieee websites place cookies on your device to give you the best user experience. . this presentation was given at a time when a 1000 horsepower ball mill was . of a new mill with a low ball charge level grinding granulated blast furnace slag . a given mineral or

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GRMS integrates the functions of crushing, grinding, drying, separating and conveying, with compact structure, covering an area of approximately 50% of that of ball mill system. And it can be laid outdoors, so that investment cost is greatly reduced; it is equipped with PLC/DCS automatic control system, can realize remote control and simple operation.

slag material grinding ball mill - esterzwinkels Steel Slag Grinding Machine. Steel Slag Grinding Machine Ball mill is successfully made use of for polishing Crushing grinding mixing of various different types of products Separated iron particles from magnetic separator which is not 100 pure metal because few sand particles are still attached with iron particles due to rusted material

Vertical coal mill uses 20% to 40% less electricity than a traditional air-swept ball mill for the same amount of grinding task. Great Drying Performance. Air-swept milling method allows our mill to handle coals of up to 10% moisture content via varying its air flow rate and temperature.

slag mill processing plant

slag mill processing plant

The process is highly flexible; and the compact slag mill processing plant can be applied to any furnace configuration. Modern condensation concepts and closed loop water circuits ensure best available environmental control.

In China, there are about 30 steel slag cement plants with a combined annual output of 4.8 Mt. However, steel slag quality varies and it is difficult to process, which limits its use. If the total worldwide BOF and EAF steel slag resource of 100 Mt to 200 Mt per year was used this way, the CO2 reduction potential would be 50 Mt to 100 Mt per year (IEA, 2008). The use of slag mill processing plant as a cementing component should be given a priorityfor technical, economic, and environmental reasons.

steel slag - an overview | sciencedirect topics

steel slag - an overview | sciencedirect topics

Steel slags (SSs) are usually classified according to the type of furnace in which they are produced. The properties of the slag depend on the type of process used to produce the crude steel, the cooling conditions of the slag and the valorisation process.

In the primary process, crude steel is produced in two ways. In the first method, the iron is produced from ore in the BF, thus, generating BF slag (BFS). BBOF slag (BOFS) is produced in the steelmaking process by using the molten iron coming from the BF. In the second method, slags are generated in the scrap-based steel industry. The first stage of the scrap-based steel industry production generates EAF slag (EAFS) and a second stage is performed to refine the molten steel. The slag produced in the LF (LFS) is the result from steel refining and, therefore, it is generally a heavy metal carrier such as chrome, lead or zinc (CEDEX Ministerio de Fomento, 2018). Table 7.1 shows the characteristics of the main slag types generated by the crude steel industry.

Another aspect that determines the physical and chemical properties of the slag is the type and speed of cooling. If the cooling of the molten slag is performed slowly, the components crystallise into stable structures producing, in most cases, a dense and inert crystalline material. However, if the cooling is rapid, its components are fixed in an amorphous structure and, therefore, the slag is unstable or active in the presence of certain substances. This is the case of the granular BF slag (GBS) which presents hydraulic properties if it is rapidly cooled and is widely used as a partial substitute of clinker in Portland cements.

There are two types of BFS, see Fig. 7.1, depending on the speed of cooling. The air-cooled slags (ABS) are subjected to a slow reduction in temperature (generally to air) and, therefore, have a crystalline structure and physico-chemical stability. Once cooled, the ABS is crushed and sieved according to the geometric characteristics required by the application. The ABS has a density of around 2.5g/cm3 and is used as a concrete aggregate, for bases, subbases and road layers (EUROSLAG; Liu et al., 2013; Nippon Slag Association). The Spanish Instruction for Structural Concrete (EHE08) (Ministerio de Fomento Gobierno de Espaa, 2008; Martn-Morales et al., 2011) only allows the use of BF ABS as aggregates, provided that the requirements regarding sulphate, sulphur and volumetric stability are met.

GBS, see Fig. 7.2, present hydraulic capacity due to its amorphous or vitreous structure. Its chemical composition is the same as that of ABS, but the structure and the stability are different. To obtain rapid cooling so as to obtain a vitreous structure, the slag is granulated. After that, the ABS is ground to sizes below 100m. ABS exhibits cementitious properties and so it is highly appreciated and used in the manufacturing of Portland cements (EUROSLAG; Liu et al., 2013; Nippon Slag Association). In Spain, 100% of produced GBS are used by the cement industry.

BOFS, see Fig. 7.3, present a high content of Fe, so its specific gravity is above 3g/cm3. This type of slag is cooled slowly to cause the crystallisation and stabilisation of its components. The most widespread use is in aggregate production for concrete and road applications (Shi, 2004; Tossavainen et al., 2007; Das et al., 2007; Juckes, 2003; Mahieux et al., 2009; Poh et al., 2006; Shen et al., 2009; Waligora et al., 2010; Xuequan et al., 1999).

The two types of EAFS are presented in Table 7.1: stainless steel (EAFS-S), Fig. 7.4 (Johnson et al., 2003; Huaiwei and Xin, 2011; Rosales et al., 2017), and crude steel (EAFS-C) (Shi, 2004; Tossavainen et al., 2007; Barra et al., 2001; Luxn et al., 2000; Manso et al., 2006; Tsakiridis et al., 2008). The main differences lie in the SiO2 and Fe contents. The high amount of oxide or metallic Fe (which could not be recovered) gives the EAFS-C, Fig. 7.5, a density which is usually above 3.5g/cm3. It is estimated that for each tonne of steel produced in this furnace, between 110 and 150kg of EAFS are generated (UNESID, 2018). When they are used as aggregates, after slow cooling, they have high compressive strength and skid resistance. EAFS have been shown to be high-performance aggregates in high-strength concrete and in road layers.

LFS, see Fig. 7.6, is commonly generated in the production of low-alloy steels and after air cooling and weathering over several days, this material is completely ground into fine white particles (Manso et al., 2005, 2013). Depending on the type of process, two types of LFS can be found. Those saturated with alumina (Tossavainen et al., 2007; Adolfsson et al., 2007; Nicolae et al., 2007; Yildirim and Prezzi, 2011) and those saturated in silica (Manso et al., 2013; Qian et al., 2002; Papayianni and Anastasiou, 2006, 2010; Branca et al., 2009; Rodriguez et al., 2009; Setin et al., 2009; Montenegro et al., 2013). They differ in their composition, having either a higher content of aluminium oxides or a higher content of silica oxide. LFS can be used as raw material in the production of cement, although special care should be taken with the content of fluorine and chlorine, which could adversely affect the properties of the clinker. It accounts for between 10% and 20% of EAFS production (UNESID, 2018).

As has been known, the major concerns with the use of BOS slag in SSBC manufacture have been associated with two issues. One is whether the BOS slag has sufficient volume stability during its service period. If the stability of SSBC is not acceptable, it will lose service significance. The second issue concerns the grindability of BOS slag used in SSBC manufacture. As is known, the main energy consumed during cement manufacture is in the process of calcining and grinding. If the energy consumed in steel slag grinding/magnetic separating is more than that for calcining and grinding of raw materials and clinker, BOS slag will lose its economic significance as an additive of blended cement. Although several papers have been published dealing with steel slag use in blended cement, few have addressed the grinding aspect and little careful laboratory investigations of steel slag grinding phenomena seem to have been done to date. It is considered that the energy consumed in relation to calcining and grinding of raw materials can be saved when using steel slags as active additive materials. However, several questions exist as to the degree of grindability of BOS slag and how it compares with OPC clinker and other materials, the suitable mill feeding size and the overall assessment of grindability.

It is well known that steel slag contains similar mineral composition to that of clinker; however, because of composition fluctuations, the slag may become unstable due to excess free CaO. GBFS possesses hydraulic properties that can only be activated in the presence of an existing basic or sulfate activator such as CaO or CaSO4 (Asaga, Shibata, Hirano, Goto, & Daimon, 1981; Duda, 1987; Narang & Chopra, 1983). Steel slag contains excess CaO that could constitute this activator. These factors comprise the premise for using steel slag as a component material for SSBC manufacture. Experiments have proven that the combined use of steel slag with GBFS and/or OPC clinker can balance the composition fluctuations in the steel slag and some CaO in the steel slag can be absorbed by GBFS, thereby preventing the occurrence of instability of SSBC specimens.

Despite differences in respective quantities of the chemical and mineral constituents that exist between steel slag and OPC clinker, steel slag can be considered comparable with OPC clinker. These differences do not affect the potential use of steel slag as an active material.

Magnetic reseparation of the steel slag can improve the efficiency of intergrinding steel slag and OPC clinker by about 50% compared with intergrinding OPC clinker and nonmagnetically reseparated steel slag. The grindability of mixtures of steel slag and OPC clinker depends on the relative content and initial pregrind size of the steel slag. No decrease in grindability was measured when less than 20% of 2.364.75mm steel slag was added to the OPC clinker.

SSBC paste specimens were inspected when cured. No cracking on the surface of the samples was observed under standard curing conditions for a period of 60 days. Two specimens of each mix, cured in water for 28 days, were treated by saturated steam at 3bar (137C) for 50min. The treatment cycle consisted of 50min presoaking (temperature and pressure build-up), 50min soaking time, followed by 50min cool down period with gradual pressure reduction. Specimens from mixes of BOF slag 1 and 2 exhibited no cracking even after 100min of treatment under the same pressure. The treatment condition is more harsh than that for testing the effect of MgO on OPC. This indicates that the addition of 10% OPC clinker can effectively prevent the occurrence of instability in SSBC (Wang, 1992).

Ratio of early to late strength: the SSBC has higher strength ratio compared with OPC, strength of SSBC at 1 year increases by 152166% of that at 28 days (45.8MPa at 28 days), whereas for OPC it takes 5 years for the strength to reach 150% of 28-day strength;

Grindability is of major importance in the manufacture of slag blended cement. In terms of grindability, BFS is slightly more abrasive than clinker and cogrinding has to be performed with care (Alanyali et al., 2009).

The laboratory results are inconclusive in determining the efficiency of intergrinding steel slag and OPC clinker. Lowrison (1974) reported the Bond index for grindability of different materials: corundum 3035; silica sand 16; cement clinker 15; slag 11 (type of slag not specified).

In a SSBC pilot study conducted by the author, although the weight retained on the 75m sieve for steel slag was higher than that for OPC after grinding, about 30% of the amount of coarse OPC particles still remained as unground particles in the ball mill. This phenomenon did not occur for the steel slag. Judging from the strength of OPC and steel slag, the hardness of steel slag should be close to that of OPC. The main reasons why steel slag may be considered to be difficult to grind may be due to the incorporation of iron scrap. In the laboratory experiments reported here, about 22% by weight of steel slag was attracted by the reseparation magnet, the separated slag particles consisting mainly of fine iron particles. Nonremoval of these materials would make the slag much more difficult to grind. Magnetic reseparation is absolutely necessary, if the steel slag is to be used for manufacture of SSBC, and to ensure that the very fine particles are removed because most of them contain impurities and iron, which affects the quality of the SSBC and decreases the grindability.

Although the grindability of steel slag is rarely covered in the literature, it is of major concern in the manufacture of SSBC. Preliminary work was carried out by using a laboratory ball mill to investigate the grindability of the steel slag and OPC clinker when ground separately and interground for periods of 30 and 60min. OPC clinker having particle sizes in the range of 8.013.2mm and steel slag having particle sizes in the range of 8.013.2mm and 2.344.75mm were used in the test. Comparative tests were performed for magnetically reseparated steel slag, ordinary steel slag, and OPC clinker. The degree of grindability was assessed by particle size distribution. Results of 30min grinding have similar trends.

when 2.364.75mm particle size steel slag is interground with OPC clinker, the grindability of the composite is better than that of OPC clinker provided that the content of steel slag in the composite is not greater than 20%.

Selective use and quantification of steel slag having suitable properties are important aspects for manufacture of SSBC. The slag should be magnetically reseparated prior to grinding for SSBC. Both too fine and too coarse particles are not suitable for SSBC. If particles are very fine, impurities such as dust might be incorporated; if they are too coarse, additional crushing will be necessary and, thus, more energy will be consumed. Particle sizes within a certain range, probably 215mm, should be selected for SSBC manufacture. The incorporation of steel slag with particle size below 5mm can benefit the grinding of OPC clinker. Other particle size materials should be used for other applications (eg, road base, etc.). The addition of steel slag, at content levels of up to 20% of total solid material, is suggested as optimum with regard to stability, economy, and strength of the blended cement.

It is well known that steel slag contains similar mineral composition to that of OPC clinker; however, because of composition fluctuations, the slag may become unstable due to excess free CaO. GBFS possesses hydraulic properties that can only be activated in the presence of an existing basic or sulfate activator such as CaO or CaS (Asaga et al., 1981; Duda, 1987; Narang & Chopra, 1983). Steel slag contains excess CaO that could constitute this activator. These factors comprise the premise for using steel slag as a component material for SSBC manufacture. Experiments have proven that the combined use of steel slag with GBFS and/or OPC clinker can balance the composition fluctuations in the steel slag and some CaO in the steel slag can be absorbed by GBFS, thereby preventing the occurrence of instability of SSBC concrete.

BOS slag is produced during steelmaking by the basic oxygen process. The manufacture of steel involves the removal of excess quantities of carbon and silicon from the iron by injection of oxygen and the addition of small quantities of other constituents that are necessary for imparting special properties to the steel. A lime or dolomite flux is used that combines with the oxidized constituents to form a slag. BOS slag is decanted off from the surface of the molten steel and is normally cooled slowly, by air-cooling or water quenching, in pits or bays prior to being dug and transported to holding areas.

Despite differences in respective quantities of the chemical and mineral constituents that exist between steel slag and OPC clinker, steel slag can be considered comparable with OPC clinker. These differences do not affect the potential use of steel slag as an active material. The main differences are summarized in Table 13.6.

The addition of steel slag to the OPC clinker has to be considered in terms of f-CaO content of steel slag, total f-CaO content of SSBC, and grindability. From the results of grindability, it is known that, from grindability considerations, the optimum addition of steel slag is below 30% of total weight of SSBC (BOS slag and OPC clinker). In addition, the total f-CaO content of SSBC should be less than 2%, which is an acceptable limit for OPC and there should also be a relationship controlling the addition of BOS slag depending on its f-CaO content. From this criterion it can be shown that, provided the relative content of steel slag is controlled, steel slags with a high free calcium oxide content can be used as an ingredient of SSBC. These steel slags would not normally be suitable for other engineering applications. The addition criterion, in terms of f-CaO content, is as follows:

For a given steel slag with 1.6% f-CaO content and OPC clinker with 0.5% f-CaO, if a mixture comprising 20% BOS slag and 10% OPC clinker is interground, the resultant SSBC will be volumetrically stable if f-CaO<2%. Substituting the values into Eq.(13.2), the f-CaO content of SSBC is 0.72%. This is less than 2%, and therefore the mix is of acceptable stability.

A SSBC contains 10% OPC clinker, with 0.5% f-CaO, and 20% BOS slag. What is the maximum allowable f-CaO for the BOS slag? Substituting into Eq.(13.4) gives an answer of 11%. This means that steel slag containing<11% f-CaO can be used in SSBC.

If steel slag is used, natural resources can be preserved in steel industrial areas. Slag can be used for various purposes. There is much more to explore about steel slag as a civil engineering material, including the following:

Steel slag is an industrial byproduct obtained from the steel manufacturing industry. It is produced in large quantities during steel-making operations that use electric arc furnaces. Steel slag can also be produced by smelting iron ore in a basic oxygen furnace. According to methods for cooling molten steel slag, steel slag is classified into five types: natural air-cooling steel slag, water-spray steel slag, water-quenching steel slag, air-quenching steel slag, and shallow box chilling steel slag [47,48]. Most steel slag contains a high content of Fe1-O and other metal oxides. Fe1-O includes FeO, Fe2O3, and Fe3O4, all of which are nonstoichiometric compounds, so Fe1-O has the properties of a semiconductor. The electrical resistivity of FeO and Fe3O4 is 5102 and 4103cm, respectively, which is basically the same as that of pitch-based carbon fiber. As a result, steel slag presents good electrically conductive properties [23]. In addition, steel slag can be used as aggregates in concrete to replace natural aggregates, because it has favorable mechanical properties, including strong bearing and shear strength, good soundness characteristics, and high resistance to abrasion and impact. Steel slag aggregates are fairly angular, roughly cubical pieces with a flat or elongated shape (as shown in Figure2.13 [49]). They have a rough vesicular nature with many non-interconnected cells, which gives a greater surface area than smoother aggregates of equal volume. This feature provides an excellent bond with concrete binder. Replacing some or all natural aggregates with steel slag is helpful for reducing environmental pollution and the consumption of resources [47,48]. Therefore, steel slag is a promising kind of filler because it works as both functional filler and aggregate. The incorporation of air-quenching steel slag of 0.3155mm (in which the content of Fe1-O is over 30%) into concrete to fabricate mechanically sensitive concrete was investigated by Li etal. in 2005 [21]; subsequently, Jia performed a systematic study of this concrete (as shown in Figure2.14) [23,50].

Property modification of steel slag was conducted after steel slag was discharged to improve the stability of steel slag. Tests in some countries have shown that adding blast furnace slag or fly ash to the steel slag improved the stability of steel slag. Some research programs resulted in patents that were reflected in Japanese Patents (JPs). These included the addition of materials containing silicate or aluminate into steel slag during discharge (JP 74-58107); putting fine steel slag into molten blast furnace slag (JP 76-61278); adding boric acid or borate into steel slag (JP 78-43690); and mixing molten BOS slag with special steel slag containing Cr2O3 to raise the content of Cr2O3 above 2% (JP 78-30997). The aim of all of these methods is to eliminate the unstable materials in steel slag.

Steel slag has become one of the major sources of aggregates for highway pavement constructions in many state Departments of Transportations (DOTs) in the United States. In the past decades, the use of steel slag in HMA pavements has proven to be extremely successful nationwide. In particular, steel slag is one of the superior aggregates for constructing smart HMA pavements for heavy truck traffic, including SMA and thin, and ultra-thin, HMA overlays, due to its unique physical and mechanical properties, such as hardness, durability, and surface texture. Another potential use for steel slag is for high friction surface treatments (HFST) that are increasingly catching the attention of pavement engineers as an effective solution to addressing high friction demand on horizontal curves. Although steel slag does not have a PSV similar to that of calcined bauxite, its local availability and low price make it a viable aggregate source for HFST, particularly for less severe geometric conditions or relatively large scale projects (Li, 2016).

In Fig. 10.7 a 19mm thick 4.75mm dense-graded HMA pavement has been placed on an interstate highway. The aggregate is compromised of 39% steel slag by weight. The pavement has performed satisfactorily with reference to surface friction and ride quality. Fig. 10.8 shows HFST test patches of steel slag lying on a multilane highway. The test patches are composed of a layer of 13mm steel slag bonded to the existing pavement surface using a specialized resin binder. These test patches functioned very well in terms of surface friction and texture after one winter maintenance season.

For steel slag used as a coarse aggregate in a bound condition, or in a rigid matrix, such as PCC, the resulting integrity and volume stability are basically controlled by the minimum allowable stress of the matrix materials, cement mortar for instance, and the maximum expansion stress, which can be deduced from the expansion force based on appropriate modeling of steel slag particles in the matrix. A usability criterion for steel slag use in confined conditions can be developed by relating the allowable stress of a known matrix material and the maximum expansion force (stress) of a steel slag particle. Because concrete is a structurally sensitive material, one localized failure (one particle failure) will be regarded as failure of the concrete. Therefore the basic disruption model for steel slag concrete should be based on a single steel slag particle. The imperative task is to determine the expansion force of bulk steel slag and an individual steel slag particle.

From the expansion force test, if the bulk steel slag sample is placed in a rigid mold and the volume expansion is completely constrained, an internal expansion force will result. The expansion force is expressed as Fex and is defined as the resultant expansion force produced by a given volume of steel slag. The expansion force is to be proportional to the volume of slag sample; that is, the greater the volume of the steel slag, the larger the expansion force will be.

where fex is the expansion force generated by a dense compacted steel slag in a unit volume, (N/m3); Fex is the measured expansion force produced by a given volume of dense compacted steel slag, (N); and Vsl is the volume of compacted steel slag, (m3). The expansion force of a unit volume of slag given by Eq.(12.17) is equal everywhere in a given volume of steel slag; that is, fex is a constant for a given slag sample. Note that this applies only to the large amount of steel slag particles in a compacted condition; it does not apply to a single steel slag particle. The three-dimensional expansion force is monopolized by expansion of steel slag in a confined condition. Both the disruption ratio, R, and expansion force, Fex, will be used in quantifying the expansion force of steel slag.

where Fec is the expansion force produced by the coarse steel slag aggregate in one cubic meter of concrete, (N); Vsc is the volume of steel slag aggregate in one cubic meter of concrete, including air voids, based on the mix proportion, (m3). From a given concrete mix proportion, with the weight of the steel slag coarse aggregate and the density of a given steel slag, Fec can be calculated.

It is reasonable to assume that only the cracked or powdered steel slag particles that have undergone the autoclave disruption test contribute to the expansion force, and the disruption ratio is equivalent to the volumetric ratio. Therefore, the actual volume of expanded steel slag, (Vse), excluding air voids, is

where Vse is the actual volume of expanded steel slag particle in concrete, (m3); is the solid volume of spheres under tightly compacted condition, which is approximately 67% (Shergold, 1953), assuming maximum volume of single-size steel slag particles occupied the volume.

where Fss is the expansion force from a single steel slag particle, (N); Vss is the volume of the single steel slag aggregate particle, ((d3)/6) (m3); and d is the nominal particle size of the steel slag aggregate, (m). The equation is illegal when R=0; that is, when the steel slag particles are volumetric stable (disruption ratio is zero) or the aggregate is natural aggregate (disruption ratio is zero).

Steel slag is a calcium-rich industrial waste. Direct aqueous carbonation is one of the routes to slag carbonation. The reaction mechanism of direct aqueous carbonation of steel slag is first discussed. Various models have been proposed to model aqueous carbonation of steel slag. The merits and shortcomings of these models are discussed. A recently proposed slag carbonation model by Gopinath and Mehra (2016) is discussed in detail. The model considers the armoring of reaction surface by two secondary phases: pore closure in one of these layers due to product precipitation and the kinetics of the reaction at the slag core. The model is analyzed, its advantages and drawbacks are discussed, and further improvements to the model are suggested.

Solid steel slag exhibits a block, honeycomb shape and high porosity. Most steel slag consists primarily of CaO, MgO, SiO2, and FeO. In low-phosphorus steelmaking practice, the total concentration of these oxides in liquid slags is in the range of 8892%. Therefore, the steel slag can be simply represented by a CaO-MgO-SiO2-FeO quaternary system. However, the proportions of these oxides and the concentration of other minor components are highly variable and change from batch to batch (even in one plant) depending on raw materials, type of steel made, furnace conditions, and so forth.

Steel slag can be air-cooled or water quenched. Most of the steel slag production for granular materials use natural air-cooling process following magnetic separation, crushing, and screening. Air-cooled steel slag may consist of big lumps and some powder. The mineral composition of cooled steel slag varies and is related to the forming process and chemical composition. Air-cooled steel slag is composed of 2CaOSiO2, 3CaOSiO2 and mixed crystals of MgO, FeO, and MnO (ie, MgOMnOFeO), which can be expressed as RO phase. CaO can also enter the RO phase. In addition, 2CaO-Fe2O3, CaOFe2O3, CaOROSiO2, 3CaORO2SiO2, 7CaOP2O32SiO2, and some other oxides exist in steel slag (Sersale, Amicarelli, Frigione et al., 1986; Shi, 2004). It was reported that the X-ray diffraction pattern of steel slag is close to that of Portland cement clinker.

Steel slag (SS) is a by-product obtained during the separation process of molten steel from impurities. Selected physical properties of steel slag are shown in Table 10.1. Depending on the used production technology, the steel slag can be divided into a basic oxygen steel slag, an electric arc furnace slag and a ladle furnace slag (De Brito and Saika, 2013). The steel slag is used as a secondary cementitious binder, or aggregates for road construction (Sheen et al., 2013; Manso et al., 2004).

Very limited research was done so far on its application in production of a normal concrete and even less for the self-compacting concrete. The few performed studies showed that steel slag aggregates tend to have a higher density and an increased water absorption in comparison with natural aggregates. At the same time the abrasion resistance tends to be enhanced (Anastasiou and Papayianni, 2006). Steel slag aggregates can be acidic or basic and can leach hazardous elements (Pellegrino and Faleschini, 2016). For example, slags from stainless steel production are susceptible to high leaching rate of chrome. The electric arc furnace slag aggregates showed tendency to expand, which is related to the presence of certain volumetrically unstable periclase and free line (Evangelista and de Brito, 2010).

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