De Airing Pug Mill

Hollow Clay Products

Mechanize and Make your Tile Manufactory

RESOURCE EFFICIENT

                                                                      

After food, shelter is most important to all living beings. For human beings, shelter is not just a protective dwelling arrangement. It’s a concrete statement of his social importance and position.

It’s an externalization of his inner designs, an emphatic declaration of his own personality.

Community living is not in vogue, these days; most live in molecular families. This trend has considerably increased the need to construct new houses. Not only houses, man construct many buildings to house institutions like schools, hospitals, offices etc.

Exponential increase of the human population also caused an increase in construction of buildings.

It’s our duty to see that the buildings are constructed using natural building products to make it eco-friendly, and inflict lesser harm on the environment.

Bricks and other terracotta building products are really too eco-friendly. They are available in plenty also. Clay is the most important raw material used in the manufacture of terracotta building products. Clay is a scarce resource. It’s getting depleted fast.  So care should be taken to make as much flawless products as possible from the available raw materials.

Optimum resource utilization is the buzzword that cannot be neglected.  The main concern hence is how to minimize raw material usage and optimize the productivity.

Better Clay Management:

Raw material management is the most reliable activity to improve the final quality of any product.  Make your raw material flexible enough so that you can mould any product as per your innovative imagination.  Go to the market and learn what it needs.  Mould your products according to the needs.  Market needs alone should not be the criterion in choosing your product mix.  The society’s needs also should be given a due attention while arriving at product mix and design decisions.  The process you follow in the manufacturing of your products is to be fault free.   

The Process:

In brick or tile manufacturing, the process is to be read in association with the machinery you use.  Since there’s no much additives or other processing chemicals other than different kinds of clay, the transformation brought in by each machinery, at various stages of the clay management process is the important factor involved in the “Total Process”. This also helps in making the produce resource efficient.  This imparts the final quality of the end product too.

So a description about the machinery mix you require to make resource efficient clay products with its utmost possible quality is just the same as describing the process involved and technology adopted.

The Bare Essential Machineries Required for a Small Unit:

We will begin from the clay pit.  The process begins from there.  While dumping the clay in the clay pit please take a little extra care.  First decide on the raw material mix and its proper proportion.  Unload each ingredient of the raw materials, like lean clay, sandy clay, plastic clay and any other utilizable bi products-industrial or organic- in its right place segregated from each other.  Make it a practice to use the same place for each ingredient all the time.  The proportions in which you want to use these materials should be decided first, based on empirical data. Install Box Feeders here. The number of box feeders may vary as per your final output requirement.

The Box Feeder:

The First machine you should install in the clay yard is a Box Feeder.  The box feeder homogenizes the clay and mixing of water is made uniform, though out the column of the clay. Box Feeder also helps us ensure the different clays like Plastic Clay, Sandy Clay, Lean Clay and other utilizable, industrial or organic bi-products are mixed in its right proportion and fashion.  Feed the box feeder with the whole ingredients in its intended proportions.  Box Feeder not only homogenizes the clays but also ensures an even feeding to all the ensuing machineries. No under loading; no overloading.

Install a Pan Mill nearby and feed the output from the box feeder to this Pan Mill.  It’s called the pre crushing stage and helps us to eliminate hard pebbles and other crushable materials and to expand the clay volume. 

Pan Mill:

The first roller of the Pan Mill Squeezes and Grinds the clay. The scrappers wipe and place the clay into the second roller which down pushes the clay in noodle form. The purpose is to grind particles like pebbles or laterite lumps into finer manageable particles. Alternatively you can go for a Crushing Roller or Crushing Roller Clay Mixer in the place of the Pan Mill

The Output from the pan mill is ground using a Roller Grinder.  This is the Pre Grinding phase.

Roller Grinder:

A Roller Grinder grinds the clay particles to small size.  At the pre grinding stage itself and the clay becomes really ready for kneeding.

Spread the output from the Grinding Roller evenly in clay pit and keep it there for at least 48 hours.  This is to make the distribution of water even throughout the clay.  This stage is called pre-curing.  It greatly enhances the end quality of the product and improves resource efficiency.

Install a bucket excavator here.

The Bucket Excavator:

 The bucket excavator can chip out the clay in thin layers taking a slice from all the ingredients of the raw materials stacked in the pit.  It takes out the clay in thin wafers and can be directly or through belt conveyors fed into the ensuing machine. The bucket excavator has universal arm and can easily chip out the clay from any part of the pith.  This makes water penetration easy and can help in saving water.  It can also augment intra particular water distribution. The next machine you should install is a clay mixer. 

Clay Mixer:

The Clay Mixer is a two barreled machine. In the open barrel there are beater like paddles which expands the clay.  In the closed barrel there are continuous augers.  This compresses the clay.  The added water gets further mixed up in the column of the clay and the clay gets well kneaded.  It ensures a proper mixture of the raw material in the initial stages of the process.

At the mouth of the clay mixer there are rotary slicers which cut the emerging clay column into thin slices. The next machine you should go for in a minimalist plant is a Fine Grinding Roller.

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Fine Grinding Rollers:

The fine grinding rollers grinds the clay into finer particles.  This is very essential to render the clay particles attain the smallest possible size and uniformity, apart from helping it mix with water uniformly.  It greatly improves the strength and finish of the end product.  The aesthetics also is bettered by this stage in the processing.

It also helps in reducing the breakage rate considerably.  The Output from the Rollers can be put into a Pug mill. This Pre-pugging stage sometimes avoided in order to reduce the initial investments or to reduce the throughput time.  The pug mill extrudes the clay in columns. It’s cut into smaller slabs and is stacked inside the yard for a minimum of 48 hours.  This is the Curing stage.  This pre-pugging and curing greatly improves the quality of the products and makes it on par with the internationally expected standards. Even though the pre-curing, Pre-pugging and curing stages of the process greatly increases the throughput time by around 100 hours it’s advised you go for it, to have a peerless quality for your products.

The cured clay slabs are fed into a de-airing pug mill, for the final extrusion and finally cutting it into various product.  

De-Airing Extruder Mill:

The main aspect of the clay processing is to render it most plastic like.  Manageability of the clay is thus greatly improved.  This is achieved using a De-Airing Extruder. It is an indispensable part of any method of Clay processing.

It removes air caught inside clay column.  It makes the products possess the needed porosity and level of water absorption.  This machinery makes your manufactory most versatile.  Any product of your desired design can be extruded out through the mouth of this machine. De airing pug mills are available in many sizes to suit your production requirement.  These machineries are now manufactured in India using indigenous technology.

Hollow Terracotta Products:

Producing clay hollow wares is the need of the hour.  It maximizes your output levels and improves the quality of the product.  This method can help you achieve maximum possible levels of resource efficiency.  If you are presently manufacturing solid clay products immediately transform your industry into a modern one capable of producing hollow wares, lest you deplete the precious raw material quiet fast, and you could be penalized for that.           A Dearing Extruder makes all these transformations really possible.  After the extruder you need a fully automatic cutting table

Fully Automatic Cutting Table:

A fully automatic cutting table helps you reduce the damages caused by human handling of the green bricks (not dried).  Human handling before burning is to be reduced as much as possible since it imprints permanent marks on the product and reduces the aesthetic values and finish.  Cutting table helps you impart the required final quality to your products.

Finally you need proper driers, Kiln, trolleys and conveyors depending on the lay out of your production line and movement of the raw material from start to finish.

The Indian Scenario:

As far as India is concerned we are self reliant more or less.  Even for highly automated plants with huge production capacities India has technological sufficiency.  The above machinery mix and process pattern explained is suitable for a small to medium sized plant. The actual nature of process and machineries required may be fine tuned as per individual needs and situation prevailing at that place.

If you want to upgrade your unit to a resource efficient brick/tile manufacturing unit, you may contact me.

-Babu Appat

NB: I have consulted many resource persons to prepare this article. Some of them are Mr. KK. Vijayan, Vijayaprakash Industrials, Calicut, Kerala., Dr. KGK Warrier, Scientist-G, Deputy Director, Regional Institute for interdisciplinary science and Technology, Thiruvananthapuram., Dr. SN Misra, Scientist in Charge, Central Glass and Ceramic Research Institute, Ahmedabad., Mr. Suresh Krishna and Mr. N Vasudevan of The Energy Research Institute, New Delhi., Mr. Rudy Van Reeth and Mr. DJ Jagadeesha of Wienberger Brick Industry Pvt. Ltd, Bangalore., Dr. Damle of Damle Constructions Pvt. Ltd, Kolkatta, Mr. Dasarath, Managing Director, Anjaneya Bricks and Tiles (P) Ltd, Hoskote, Bangalore., Mr. KC Thomas, Thomson Tiles Chalakkudy, Kerala., Dr. Neelima Jerath, Executive Director, Punjab State Council for Science and Technology, Chandigarh., Mr. JK Oberoi, General Manager, Sainath Tiles and Bricks Pvt. Ltd, Ghaziabad, UP., Mr.Khulbhushan Agarwal,Proprietor, Bharat Bricks Co, Derabassi, Haryana., Mr. Jindal, Jindal Mechno Bricks, Badli, Haryana., Mr. George Mathews Pune., along with a lot other workers and supervisors of different tile manufacturing units across the length and breadth of India.  I have visited more than one hundred companies to personally verify the working pattern and process fine tuning adopted by them. I express my sincere gratitude to everyone, hereby mentioned and not mentioned, for providing valuable information in this regard and demonstrating the working of various machineries in their plants. If any important name is left out it's not intentional and is regretted deeply. Your suggestions for further improvements in this regard is most welcome.

De Airing Pug Mill