Question: What is the rate of production of a VSBK?

Answer: The rate of production varies on the number of shafts. A four-shaft VSBK with cross section 2m x 1m can produce 16,000 standard Afghan size bricks per day. Hence in a year the production capacity can be around five and half million bricks.

Question: Is VSBK a profitable business?

Answer: A VSBK is not a business but it is an energy efficient brick firing technology, allowing reduced fuel cost. The profitability of a brickyard operating VSBK depends on many other factors, which have to be well organised and managed by the entrepreneur. However VSBK offers 50% saving in coal cost. Experience in Afghanistan shows that a four-shaft VSBK can annually save up to 480 tons of coal. The cost of 480 tons of coal, at current market price, in Afghanistan would be about 2.4 million Afghanis in one year, which is more than the extra investment required for establishing a VSBK instead of a BTK. Considering the 15 years lifespan of VSBK and recent trend of 10% annual increases in the price of coal, the saving in coal cost would worth almost 75.000.000 Afghanis at the end of 15th year.

Question: Do I get a good brick quality in VSBK?

Answer: If operated optimally, VSBK produce uniform brick quality with breakage below 5%. Generally observed, compressive strength of VSBK bricks is higher than BTK bricks. However the colour and ring may vary slightly during the initial phase of the operation. But with selection of right soil and fine tuning the production process, the differences can be mitigated.

Question: How do I identify the suitable clay quality for VSBK?

Answer: Clay with higher plasticity and free from foreign materials like pebbles and roots are suitable for VSBK. For soil with a high vitrification temperature (e.g. because of a high lime content), special attention must be given to the selection of a suitable coal in order to keep the operational sensitivity as low as possible. In general if good bricks can be made in a BTK the same soil can also be used in a VSBK to make good bricks. There are also scientific methods to identify the suitable clay quality for VSBK, but the most reliable method to check the suitability of particular soil is to make and fire a few test bricks.

Question: How long does it take to construct the VSBK?

Answer: A well managed construction site with experienced supervisors can be completed within 100 days.

Question: What kinds of bricks can be fired in VSBK?

Answer: All rectangular clay bricks, either hand mould or extruded, can be fired in VSBK. Because of its short firing cycle, VSBK is suitable for the production of hollow bricks as well. Each VSBK shaft is designed for specific size of bricks hence once designed, bricks size cannot be arbitrarily altered. However, the multiple shafts of a VSBK allow flexibility to react to special market demands (e.g. by producing extruded hollow bricks for particular clients) parallel to the standard production.

Question: What kind of fuel can I use in VSBK?

Answer: VSBK is fired with low volatile coal with heating value above 4500 kcal/kg, which is usually cheaper than coal used for BTKs. For initial fire ignition, in addition to coal, about 200 kg of firewood and 5 litres of kerosene per shaft are also required. For internal fuel, combustible waste such as sawdust, boiler ash, sponge iron waste can also be used. The selection of internal fuel depends on the availability of the fuel, its cost and heating value.

Question: Do I have to build all shafts together?

Answer: No. An entrepreneur can start with a single shaft and later add on additional shafts according to the requirement. In general, the higher the number of shafts, the quicker the return on investment.

Question: Do I have to fire all the shafts together?

Answer: No. VSBK offers flexibility in operation. Shafts can be fired according to the market demand of fired bricks.