Tanzania: Firing up

Clay Technology magazine
,
18 Aug 2018

Ali Sheriff looks at how to make the leap from batch to continuous firing of bricks in Tanzania.

On its Independence Day in 1961, Tanzania’s population was nine million, and today, it is nearing 50 million. By the middle of this Century this figure could double. Traditional homes in Tanzania are mud houses with thatched roofs and walls essentially made of a wooden shell covered in unfired clay. However, with a growing economy, there is a greater demand for better building materials and a corresponding increase in safety and aesthetic standards. Cement blocks and corrugated iron sheets are currently the most common materials used as they are easily available, strong and quick to build with.

Brick production in Tanzania usually involves the use of air-dried wet slop moulds. Firing occurs in small clamp kilns fuelled by logs. From what used to be a few scattered facilities, these are becoming a common sight, with virtually all bricks being produced in this way.

In advanced economies such as those in Western Europe, tunnel kilns are a preferred method as they are mechanised and economical to operate. However, these have not been as successful in developing countries as the initial investment and sustainability of technical demands is difficult. In Dar-es-Salaam, a government parastatal, the Kisarawe Brickworks had difficulty in maintaining production. Similarly, Kijegne Clay Products, Arusha, North Korea didn’t manage commercial production.

In areas where skill level is high but manual labour is cheap – such as Bangladesh, Nepal and Vietnam, Hoffman kilns are more common. These have seen more use as brick production in these countries has increased, especially as the lower fuel requirement compared with those of batch kilns acts as an incentive. An improved version of firing has one chimney and the path of the flames moves between bricks, improving fuel efficiency further. 

The vertical brick shaft kiln (VBSK) is a Chinese equivalent of a continuous kiln and is gradually being adopted in East Asia. The Langloof Brickworks, South Africa, has started using one and intends to expand its use in coming years as it offers better efficiency both in terms of fuel and breakages. 

Kiln fuels range from wood, coal and sawdust to coffee and rice husks, depending on the relative availability of these products between different areas. In Tanzania’s case, this is no different – more than one resource could be used in various parts of the country.

In southern parts of Tanzania, where coal is available, this may be considered a better alternative to the current use of firewood, as deforestation is a huge problem. Although issues with greenhouse gases and particle emissions of coal are well known, it could be considered the lesser evil in comparison to the drought and mudslides that have been linked with the reduced land mass of forests. Furthermore, this would allow for more firewood to be used in food production, so the cost to population would not be prohibitive. Another advantage of repurposing of firewood is the supply of feed to animals, especially in a country where animals outnumber humans ten-to-one. 

Currently, every brick maker has a clamp kiln. However, the technology or investment required in more advanced kilns such as the VSBK may encourage the model of entrepreneurs offering firing services to smaller brickmakers. This would be more financially viable than firing products themselves. 

What will spur Tanzania to the next level? Various factors in combination or in their own right may promote the use of advanced kilns. For example, increasing fuel or cement prices could encourage this alternative, as well as higher demand for bricks. There are interesting times ahead. 

Ali Sheriff was involved in potteries in Tanzania for over a decade (1980–1994) and has kept contact with them since.

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