Articles on the cement industry from Global Cement

The largest country in the world,¹ Russia is also in the enviable position of having huge natural resources, including limestone, diamonds, gold, fresh water, minerals and oil.² Indeed, it ranks top in the CIA World Factbook list of oil producing nations³ and has benefitted from recent increases in the price of fuel. Russia is populous and has seen steady economic growth so far in the 21st Century. Its cement industry is also growing rapidly, although it needs significant investment and consolidation to remove older, inefficient plants. Indeed, FLSmidth recently described Russia as its 'most promising' market because of the need for more efficient plants.⁴

Introduction

The Cold War thaws

The ideological battle between Communism and Capitalism known as the Cold War was the defining backdrop to the second half of the 20th Century. On one side was the Soviet Union (USSR) and its allies in the Eastern Bloc; on the other, the USA, Western Europe and others opposed to the spread of Communism. Both sides feared the expansion of the other's ideology and sought to contain the other through a variety of means. These included a mixture of military strategy and posturing, a conventional and nuclear arms race, espionage, the provision of aid to venerable allies, proxy wars in Afghanistan, Korea and Vietnam, diplomatic appeals to neutral countries and technological, military and economic one-upmanship.

Following a series of very conservative leaders in the USSR, Mikhail Gorbachev came to power in 1985. By this time, the Soviets were fighting a losing battle against US-supplied resistance fighters in Afghanistan, which had crystallised existing public opposition to the war there. It was also in a period of economic stagnation and widespread corruption in the government.

With nearly 82 million inhabitants and a GDP of Euro2.5tn in 2010, Germany is both the most populous and richest nation in Europe.^1,2 Although its cement production industry has been muted in recent years due to the global economic downturn, the country has a strong industrial background and is a leader in many industrial sectors, including the manufacture of cement production equipment, which has enabled strong exports to developing regions of the world.

Introduction

East and West

Following defeat of Nazi Germany at the end of the Second World War, Germany was split into two sections in 1949, with the western three quarters (Federal Republic of Germany, FRG) under the initial control of France, Britain and the USA. The north-east corner became the German Democratic Republic (GDR) under the Soviet stewardship of the USSR.

While the FRG (West Germany) was allowed to rebuild its market-based economy and become re-established within Western Europe as part of the US's Marshall Plan, the GDR (East Germany), like other Soviet states, was run to a strict planned economy with centralised production targets and wage structures.

This article, based on a paper presented at the 13th International Congress on the Chemistry of Cement at Madrid in July 2011, describes a radical, step-change approach to reducing CO₂ emissions from cement manufacture.

A highly novel method of cement mineral synthesis using a molten salt process yields a fine-grained product that requires little or no grinding. The specific sustainability impacts that may arise from a molten salt route have been assessed and quantified against the conventional manufacturing route in terms of resource efficiency (energy consumption and waste output), supply chain influences and management of the production process.

World-wide, mankind produces over 3Bnt/yr of cement,^1,2 most of which is used to make an estimated 10km³ of concrete – more than an order of magnitude greater than the combined volume of all other man-made materials (Figure 2). Although the carbon dioxide (CO₂) embodied in concrete is low (0.4t/m­³) compared to other common construction materials such as glass (2t/m³), steel (10t/m³) and polymers (40t/m³),³ the sheer volume of cement produced world-wide presents a serious climate change challenge simply because of the amount of CO₂ emitted during its manufacture - almost 1t of CO₂ per tonne of product.

Introduction

A cement is any substance which binds together other materials by a combination of chemical processes known collectively as setting.¹ Cements are dry powders and should not be confused with concretes or mortars, but they are an important constituent of both of these materials, in which they act as the 'glue' that gives strength to structures. Mortar is a mixture of cement and sand whereas concrete also includes rough aggregates (Figure 1).^2,3

Because it is a major component of both of these building materials, cement is an extremely important construction material. It is used in the production of the many structures that make up the modern world including buildings, bridges, harbours, runways and roads. It is also used for facades and other decorative features on buildings. The constant demand for all of these structures, increasingly from the developing world, means that cement is the second most consumed commodity in the world after water.

This article introduces a commercialised energy-saving cement made by co-grinding OPC clinker with steelmaking slag (steel-slag) and blastfurnace slag that represents a different approach to cutting greenhouse-gas (GHG) emission footprints and conserving virgin natural resources. The cement uses only 15-30% of OPC clinker, 30-40% of steel-slag and 40-50% of blastfurnace slag (BFS), allowing for great reductions in GHG emissions, consumption of virgin natural resources and energy use by between 70% and 85%. The characteristics of steel-slag as a supplementary cementitious material are also discussed.

Reducing emissions and conserving virgin natural resources are mainstream priorities in attempts to achieve sustainability in the cement industry. Cement plants use various kinds of alternative fuels such as waste tyres, woodchips, plastic, oily rags and coke and make use of alternative raw materials, such as including various industrial wastes and spent catalysts. The application of different supplementary cementitious materials (SCM) in cement production has already been proven as the most effective way to reduce greenhouse gas (GHG) emissions from cement production by replacing the same amount of clinker. Producing 1t of clinker emits about 1t of GHG. Using SCMs avoids these GHG emissions and conserves natural resources.

Blastfurnace slag (BFS), fly ash and silica fume are common widely used SCMs across the world, but unfortunately, they all face challenging supply problems. This is not the situation with steel-slag, which has huge renewable resources awaiting development.