- Written by E. Y. Reichardt, P. Heyd, K.-P. Lukas Gebr. Pfeiffer AG, Kaiserslautern, Germany
After 25 years of mainly producing slag cement, the vertical roller mill MPS 3750 C near Hannover and supplied by Gebr. Pfeiffer AG was equipped with a modern outer material recirculation circuit and a new nozzle ring. During the acceptance test in 2006 with CEM III A 42.5 containing 40% slag, the production rate was increased by 30% at a fineness of about 5500cm²/g (Blaine). The electric energy consumption of the mill, separator and fan was reduced by 10% at the same time.
Gebr. Pfeiffer AG, a medium-sized family business, has been a supplier to the cement, lime and gypsum industries for over 140 years. The company's product range comprises machines and equipment for the grinding, classification and drying of diverse materials and for slaking quicklime and calcining gypsum, which are sold worldwide.
The company, headquartered in Kaiserslautern, employs 280 staff and maintains manufacturing facilities as well as its own foundry. Gebr. Pfeiffer AG has an annual turnover of around Euro100m. With over 2000 MPS vertical roller mills in use around the world today for grinding cement raw material, coal, clinker, granulated blast furnace slag (GBFS), pozzolana, limestone, clay, gypsum and various other materials, the MPS technology represents the company's major source of revenue.
- Written by Bill Bourke SteelServ Ltd., New Zealand
Recently it was speculated that the next World War will be over water. There are dire forecasts that many third world nations are going to run out of water as a result of climate change, while a number of first world countries, like parts of Europe and certain areas of the USA, are already experiencing unusual drought conditions. There is also growing alarm about the damage that degraded water is doing to our environment, either through the degradation of lakes and rivers through an over abundance of nutrients, or the contamination of marine silts and sediments with heavy metals that can, and in some cases already have, entered the food chain.
This paper is about the ability of the slag industry's aggregate to clean up water that has become degraded with heavy metals, either before it is discharged or before it is put to some other beneficial use such as irrigation.
Impervious surfaces are a major contributor to urban storm water (also known as surface water run-off) impacts. Storm water in turn, has been identified as a major contributor to water quality degradation, as it can have significant concentrations of harmful pollutants that can adversely affect the receiving aquatic environment. Materials that can remove harmful pollutants and can be incorporated into storm water treatment devices offer part of the urban storm water solution. Previous research into the use of iron and steel furnace slag aggregates as water filtration media has demonstrated high adsorptive capacity for various metals and phosphorus and the removal of fine particulates in the source solution.
Encouraged by previous research and some promising results obtained with slag aggregate filter beds in New Zealand, The Australasian (Iron and Steel) Slag Association (ASA), commissioned a study into the effectiveness of common iron and steel slag aggregates to remove contaminates typically found in storm water run-off, while maintaining their hydraulic performance. The study also provides data on the potential environmental effects and effectiveness of different iron and steel slags produced in New Zealand and Australia, for remediation of storm water pollution.
This paper provides an overview of the ASA commissioned study, as well as describing some of the in-field results observed with filter beds in New Zealand. A full copy of the ASA study maybe obtained by contacting the ASA, the address of which is listed in the references.
- Written by David Perilli
Turkish slag cement manufacturers are looking for new growth in sales following a steady increase in demand during the past four years, due to a sustained economic upturn and wider appreciation of blast furnace slag cement qualities by the construction industry. Progress is slow, however and while opportunities exist for consumption of slag cement to expand significantly in future, the volume of slag cement used is small compared with total potential tonnage that could be consumed each year.
Blast furnace slag in Turkey is produced by three large steel mills and a number of smaller steel plants. Two of the large plants – Eregli Steel Company and Kardemir Iron and Steel Co are located in the northern Black Sea region while Iskenderun Iron and Steel Co is located in the western Mediterranean region along with a number of smaller steel plants.
- Written by Sitthisak Wittayangkoon Siam Steel Mill Services Limited
Thailand is one of Southeast Asia's economic success stories. It has the highest levels of prosperity since the regional economic crisis of 1997. According to the World Bank, Thailand's Gross National Income (GNI) per capita of US$1980 is more than double that of the East Asia and Pacific average of US$950 in 2002. Like any other developing country the efficiency of its logistics and transportation system is a very important consideration. At the heart of this are ambitious plans to expand the country's motorway network from 225km to 4150km. With such a significant expansion on the horizon, Sitthisak Wittayangkoon argues for the use of EAF slag as an additive in road construction. He believes that making use of EAF slag will add value to a substance that has long been perceived as a problem.
At present over 90% of highway paving in Thailand is constructed from asphalt concrete. Asphalt concrete (also referred to as hot mix asphalt) is a mixture of fine and coarse aggregate with an asphalt cement binder. The mixture is compacted at high temperatures at a central plant and then placed on the road using an asphalt spreader.
The aggregate used in asphalt mixtures (hot mix asphalt, cold mix asphalt and surface treatments) comprises approximately 95% of the total mix by mass. Moreover, the stability of the mixture depends on control of aggregate grading, strength, toughness and shape. The asphalt binder, used to coat and bind the aggregate particles together, typically makes up about 5–6% of the total asphalt mixture.
Asphalt cement is also used in hot mix asphalt. Liquid asphalt, which is asphalt cement dispersed in water with the aid of an emulsifying agent or solvent, is used as the binder in surface treatments and cold mix asphalt pavements. The properties of binders are often improved or enhanced by using additives or modifiers to improve adhesion (stripping resistance), flow, oxidation characteristics, and elasticity. Modifiers include oil, filler, powders, fibers, wax, solvents, emulsifiers, wetting agents, as well as other proprietary additives.
- Written by D. Venkateswaran*, D. Sharma* L. Muhmood**, S. Vitta** *Indorama Cement Ltd., **Indian Institute of Technology
Electric Arc Furnace (EAF) slag from one of the steel plants in Western India has been characterised in detail. Its effectiveness as hydraulic material is examined before and after heat treatment in an induction furnace. The study shows that while there is a marginal reduction in the early age strength of the Portland Slag Cement mortar, the later age strength does not suffer by replacing up to 20% of Ground Granulated Blast Furnace Slag (GGBFS) by EAF slag.
The solid wastes generated during the metallurgical processes of extraction and refining are called 'slag'. They consist predominantly of oxides and silicates of magnesium, calcium, aluminium, iron etc. The slags produced during the process of iron and steel making, are broadly classified into three categories;
- Blast Furnace Slag (BFS) from the crude or pig iron production in blast furnace.
- Steel slag from a Basic Oxygen Furnace (BOF) and the Electric Arc Furnace (EAF).
- Ladle refining slag from the steel refining processes in the ladles.
The blast furnace slag after granulation and grinding finds extensive use in cement and concrete. The steel slag, however, is yet to find a value added application except for its occasional usage as a cementitious binder. More often than not it is used as a landfill material. Most of the recent work therefore has been focused towards finding and exploiting the potential advantages of steel slag as a resourceful material.
