Machine-Made Brick Soft-Mud Process

Soft-Mud Process. The clay, after being dug from the clay bank, is thrown into a pit, usually 6 feet deep, and 8x12 feet in area, lined with plank; water is then turned into the pit, and the clay is soaked for twenty-four hours. It is usual to provide three pits, so that the clay may be soaking in one, while the second is being emptied and the third filled. The clay is thrown out upon an endless chain, which carries it along to the machine, into which it falls. The upper part of the machine contains a revolving shaft on which arms are placed. These arms break up and work the soft clay, after which it falls to the bottom of the machine; here revolving blades force it forward, and a plunger having an up-and-down motion, forces the clay into a mold immediately under the plunger. When the mold is filled, it is either drawn or forced out on a shelf or table; another mold is then placed under the machine, and the filled mold is emptied by hand and the brick taken to the drying yard.

Stiff-Mud Process

Stiff-Mud Process. The difference between a soft-mud and a stiff-mud process is, that in the latter, the clay is first thoroughly ground, and just enough water is added to make a stiff mud. After this mud goes through the pug mill, it is placed in a machine having a die the exact size of the brick required. The opening in this die is made the size of either the end or side of a brick. The machine forces a continuous bar of clay through this die, and, as it emerges, it is automatically cut in the form of a brick, and then taken to the drying yard. The soft brick are placed in rows in a yard covered by a rough shed with the sides open, where they are sun or air dried for three or four days. When properly dried they resemble somewhat the "adobe" brick, formerly used for constructing houses, and still used in some of the Southwestern states and territories, and also in Mexico and Central America.

Dry-Clay Process

Dry-Clay Process. The third process, and one much used, is known as the dry-clay process. The clay is used in this method just as it comes out of the bank, and is apparently perfectly dry. It contains, however, from 7 to 10 per cent. of moisture.

The clay is first mined, either by hand or steam shovel, as circumstances may require. It is then usually stored under cover, in order that a supply may be constantly on hand, and also that it may further dry and disintegrate. In many cases, two or more grades of clay are mixed together in proper proportions, determined by trial, as the clay is thrown in the dry-pan, which is a circular machine about 4 feet in diameter, and 2 feet deep, having a perforated metal bottom. In this pan are two wheels which revolve on horizontal axles. Between these wheels and the bottom of the pan, which also revolves, the clay is ground; it then drops through the holes in the bottom of the pan to a wide belt, which passes above an inclined screen on which the clay falls. Such portions of the clay as are sufficiently ground pass through the screen on to another belt, while the coarser particles pass into the dry-pan to be ground over, and again carried to the screen for sifting.
The belt carries the finely ground clay to a mixing pan, which by constant agitation thoroughly mixes the particles.

The clay falls from the mixing pan into the hopper of the pressing machine, and thence into the molds. The loose clay fills evenly steel boxes the same width and length as the finished brick, but much deeper. Steel plungers, forced under great pressure into these boxes, compress the clay until the requsite thickness is obtained. The pressed brick is then pushed on a table, and from this the bricks are placed on a barrow or car and taken to the kiln.

Molded bricks are made in the same way, the difference being that the box is made to give the shape of the brick required. In most of the dry or pressed clay brick machines, a small jet of steam is admitted into the clay just before it enters the mold, in order to slightly moisten it, and cause the particles to cohere better.

Whenever the term pressed brick is used, it should mean the brick made by the dry process. There are many so called dressed or face brick, however, that are made by repressing soft-mud brick.

World Bank to revolutionize brick making in India

The Hindu News Update Service July 28, 2006
New Delhi, July 28. (UNI): The World Bank will help Indian companies revolutionise brick making through a novel technology that would make kilns energy efficient and will be manufactured without the use of thermal energy.

The World Bank, as trustee of the Community Development Carbon Fund (CDCF), has signed two agreements with two Indian companies to promote technologies that may help revolutionise the building material industry to utilise a more energy efficient kiln to produce burnt clay bricks, and the other replaces burnt clay brick with fly ash bricks which are manufactured without the use of thermal energy.

"These Projects will help clean up the brick industry, which is not just one of the major contributors to India as carbon dioxide emissions, but also uses up inordinate amounts of coal energy," World Bank Country Director for India Michael F Carter said.
He said it would also result in significant local environmental and social benefits. The Bank-managed CDCF will purchase the carbon credits and he hoped this will help finance the spread of these energy-efficient technologies in India.

In India, clay bricks have been extensively used for centuries and are the predominant construction material even today. Current demand is over 100 billion bricks a year. The fuel costs alone account for almost 30-40 per cent of the production cost.

The conventional practice of firing clay bricks in traditional kilns consumes large quantities of coal, firewood, and other biomass fuels. The Indian brick industry, which is the second largest producer in the world, next to China, consumes more than 24 million tons of coal annually.

Brick making is a traditional, unorganised industry, generally confined to rural and semi-urban areas. It is one of the largest employment-generating industries, employing millions of workers.

The Vertical Shaft Brick Kiln (VSBK) technology project aims to improve the thermal performance of the brick manufacturing units in selected clusters of the country, especially in the states of Chattishgarh, Madhya Pradesh, Rajasthan, Orissa, Jharkhand, Uttar Pradesh and West Bengal.

This technology is both cleaner and more energy efficient than the clamp technology, which is commonly used by the small and medium scale brick manufacturers.

Technology and Action for Rural Advancement (TARA), the agency which provides the VSBK technology in the country, intends to set up a total of about 126 VSBK plants, in a time frame of two to three years in selected clusters in the participating states through different entrepreneurs.

The almost 4,00,000 tons of greenhouse gas emission reductions generated by the project over 10 years will be purchased by the CDCF.

TARA, the social enterprise arm of the Development Alternatives Group, has played a key role in introducing and adapting the technology to India. TARA will be the implementing agency for the project.

"The TARA Eco-Kiln, the first major innovation in brick-making in several centuries, is the only solution currently available to replace conventional brick-making technology and save the countryside from air pollution and the small and medium enterprise segment of the industry from oblivion," said Dr Arun Kumar, President of TARA.

"With a rapidly growing demand for bricks every year in our country, already at 160 billion, and the huge saving it enables of greenhouse gases emitted into the atmosphere,"

The project will also deliver community benefits to the VSBK workers including provision of health insurance and accident coverage for brick workers at the project sites; provision of basic sanitation facilities for men and women; employment for a longer period), minimising the need for alternative employment.

The second project is the FaL-G project. The initiative will replace environmentally damaging burnt clay building bricks in India's construction sector with fly ash brick, which is manufactured using available industrial wastes/by-products as basic raw materials. Burnt clay bricks are predominantly used as walling material by the construction sector in India. The process of producing the brick requires fossil fuel consumption and denudation of fertile topsoil.

Fly ash, the key ingredient of FaL-G technology, is a byproduct from coal power plants and abundantly available in India. Fly ash is mixed with two other ingredients: lime, which is a byproduct of the acetylene industry and gypsum from chemical plants. This blending recipe is a revolutionary invention, as this technology does not require a sintering process in brick production. No thermal energy is required and consequently no greenhouse gases are emitted.

The project will facilitate setting up about 100 micro industrial plants in different parts of the country, particular in the states of Tamil Nadu, Kanataka, Orissa and Utter Pradesh, by micro enterprises to manufacture fly ash bricks using the FaL-G technology.
" I hope that, with the World Bank's assistance in fetching carbon revenues, entrepreneurs would generate much more enthusiasm, contributing to the rapid proliferation of the technology to meet our company's vision, said N. Kalidas, Executive Director of Eco-Carbon and founder director of INSWAREB (Institute for Solid Waste Research and Ecological Balance).

The CDCF will purchase 600,000 tons of greenhouse gas reductions over a 10 year period from the FaL-G project. The FaL-G project will deliver community benefits as well: Provision of health insurance and accident coverage for workers; improved living condition for workers (toilets, drinking water and washing/bathing facilities) and year round employment for workers (compared to seasonal employment in the clay brick industry).

The construction sector in India is considered one of the most carbon intensive sectors representing about 17% of India's carbon dioxide (CO2) emissions, roughly equal to 170 million tons of CO2 emissions per year. The Government of India has already committed to banning clay bricks in urban centers; both the FaL-G and VSBK brick-making technologies and the potential they hold for reducing climate altering greenhouse gases demonstrate a technological solution that is economical for traditional brick producers.

The Kyoto Protocol and the Clean Development Mechanism (CDM) The Kyoto Protocol provides an unprecedented opportunity for the Organisation for Economic Co-Operation and Development (OECD) countries to reduce greenhouse gas emissions and at the same time help developing countries and economies in transition invest in climate friendly technologies and infrastructure.

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The Clay Brick Industry:

Improvement of Resource Efficiency and Environmental Performance

The clay brick production industry is a major source of air pollution in developing countries.  The major issues in environmental improvement involve improving the combustion efficiency of existing kilns, and upgrading kilns to newer and more efficient process designs.  Most of the cleaner production effort has been in India, where a number of studies and improvement projects have been conducted.  The amount of information on the web about CP in this industry is relatively low.  Process technology upgrades are usually capital intensive in this industry.  Combustion efficiency improvements can be achieved with relatively low costs in many kilns.  Promoting cleaner production in this industry requires extensive understanding of and work with the brickmaking community because there are many social and economic factors affecting potential technology changes.

The table below lists several low-cost ways to reduce waste and pollution in brick making.  Company environmental programs should demonstrate that these options have been considered thoroughly. Direct links to online guides for cleaner production in clay brick making follow the table.

Solutions to Increase Efficiency and Reduce Waste in Clay Brick Production  

Kerala brick industry taking over rice fields

IMMEDIATELY after the monsoon, most of the paddy-fields in central Kerala are prepared -- not for cultivation, but for brick making!

IMMEDIATELY after the monsoon, most of the paddy-fields in central Kerala are prepared -- not for cultivation, but for brick making! Brick-making has been gaining momentum during the last 15 years because it is easy money. From about one hectare of paddy-field leased from farmers, a brick manufacturer can rake in a whopping annual profit of more than two lakh rupees. And, because the brick manufacturer can afford to pay more, most of the women who used to work in paddy-fields have switched to the brick industry.

Raw materials for brick-making are available cheaply -- water from the river, clay from the leased field and fuel wood from pest-affected coconut palms. As the labourers are daily wage-earners and are not registered, there are no strikes, unlike in other conventional industries.

Brick boom Because of the spurt in the brick industry, Kerala's traditional tile and pottery industries face a bleak future mainly because the available clay is gobbled up by brick-makers. Tile factories enjoying state subsidy and reduced tax rates are coming up in central Kerala, but they end up producing bricks and glazed tiles because these are in demand.

Changes in Kerala lifestyles have altered traditional homes. Earlier, houses were usually made of mud or laterite stone and topped with coconut thatching or tiles. The Gulf boom in particular and the white-collar culture which began in the 1970s have popularised brick-and-concrete houses. As a result, the brick industry is expanding so fast, labourers from as far away as Thanjavur, in Tamil Nadu, are being recruited to meet the demand. Labourers from Tamil Nadu leave some of their family members behind to look after their own fields after the monsoon, while they migrate to Kerala to work in brick factories.

Most of the paddy-fields in central Kerala are located along the spur hills of the Western Ghats, which were once thick with vegetation and crisscrossed with rivulets. Excess water from these hills would flow into the paddy-fields, which functioned as natural reservoirs. But these hills have been badly affected by encroachment, illegal tree-felling and the establishment of plantations of rubber and coconut and by the construction of roads, bridges and shopping and housing complexes. All of these have reduced and fragmented vast stretches of paddy-fields.

The situation has been made worse by the brick industry, which utilises fertile fields for five to ten years and then abandons them. By then, the land has been peeled away so much, it may be several metres below sea level and impossible to return to farming. Another problem created by brick-making for small farmers is that if their holdings are surrounded by fields leased to factories, their access to river water is blocked, at times forcing them to vacate.

Even after the green revolution and intensive farming techniques that enable three crops a year, Kerala is facing an acute shortage of rice. The state's residents literally wait for railway wagons to bring food to them from the north. Last year, the state government launched a Rs 100-crore, intensive agriculture programme to increase rice production. One only hopes it isn't too late and ecologically destructive land use patterns have not ruined agriculture to the core.