How many brick kilns are in Pakistan?
According to an estimate, about 5,000 brick kilns are concentrated within the province of Punjab alone, whereas there are around6,000 in the rest of the country. Another study by Kevin Bales estimated that there are approximately 7,000 brick kilns in the country.
How many brick kiln workers are there in Pakistan?
On average, more than 100 workers are employed at one brick kiln. That makes the total labor force in this industry to over 700,000 and that was at the end of the 1990s. Today however, it is estimated to be around a staggering 4.5 million!
How are bricks made?
It’s a simple process, the soil is mixed water and kneaded into dough which is cast into molds and shaped as bricks. Then they are dried in the open and finally are stalked into the kiln.
- Bricks are heated to between 600 and 1100 °C in the kiln.
- The primary fuels are: coal, local biomass and any available low-cost fuel or scavenged fuel (i.e., waste oil, tires, battery cases, dung, etc.).
The Cons of Brick Kilns:
Traditional brick kilns emit thick black smoke containing several air pollutants (carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxides) and fine particulate matter (coal fines, dust particles, organic matter), which present serious health hazards (human illnesses, animal and plant life destruction) to communities living around them.
Brick Kiln Types:
Several types of brick kilns are employed for firing bricks, which can be classified into two categories: Intermittent and Continuous.
- Intermittent Kilns:
Intermittent kilns are the traditional types typically employed in Pakistan. In these kilns the bricks are loaded and then fired. When the baking is over, fire is allowed to die out. Next, the bricks are allowed to cool and then they are emptied. Afterward, the kiln is filled once more and fired. These types of kilns are common throughout in developing countries. They are highly inefficient and labor-intensive. Coal is the primary fuel although any other cheaper fuel available is also mixed, like tires and waste biomass. These kilns are most primitive in technology and pollution. They are basically updraft kilns and have been categorized as Clamp, Scove and Scotch
- Continuous Kilns:
In contrast, in a continuous kiln, fire is continuously kept burning. Bricks are loaded and emptied while the fire continues to burn. Continuous kilns are more energy efficient than the intermittent kilns. Either the bricks move through the kiln or the fire moves within the kiln. There are different types of technologies available within this type and depending upon the technology the productivity, efficiency and emissions vary.
The main types of continuous kilns are:
- Hybrid Hoffman:The Hoffman Kiln is a newer technology which is mainly employed as a replacement for older inefficient kilns. It is now the most widely used technology in China and has the capacity to use coal or natural gas.
- Bull’s Trench (BTK):Bull's Trench kiln (BTK) has found space in the sub-continent and is increasingly being used to replace the older technology mostly in India, Nepal, Pakistan and Bangladesh. It is based on a design developed by British engineer, W. Bull, in the late 19th century. It uses coal and a variety of other fuels, mostly solid fuels. It has two variants, namely: Moveable Chimney Bull’s Trench Kiln (MCBTK) and Fixed Chimney Bull’s Trench Kiln (FCBTK). MCBTK has been banned in a number of countries due to its high emissions.
- Habla Zigzag: A variant of Habla Kiln employs a zig zag tunnel to increase efficiency. It has larger capacity and is more efficient than other kilns. However, it needs a fan to draw air through which in turn requires a source of electricity.
- Vertical shaft (VSBK): In recent years has become a technology of choice for replacing older inefficient and polluting technologies. Unlike other continuous kiln designs where the fire moves through the kiln, in this design the bricks move through the kiln. Bricks are loaded at the top and removed from bottom. It is highly efficient and has low emissions.