A PROPOSAL FOR THE ESTABLISHMENT OF A

GYPSUM PROCESSING INDUSTRY IN PAKISTAN

INTRODUCTION:

Gypsum plaster for construction is not used at all at the present time in Pakistan, despite the presence of high quality gypsum, CaSO 4, 2H 2O (5 to 6 billion tons) available, to large extent, near the existing infrastructure and utilities that lend itself to economic open cast mining. Gypsum plaster is a well known proven technology with a wide range of uses in buildings due to the fact that it is inexpensive, easy to use product and employed universally. Over 200 million square meters are produced every year in Europe. Iran and Thailand, for example, consumes more than 8 million tons per year of gypsum plaster. The major factors responsible for its non-utilization in Pakistan were (i) low cost of cement in the past; (ii) traditional use of cement in construction; and (iii) conservative nature of builders, engineers, architects and masons. Now the cement prices have soard from Rs 210 to Rs 300 per 50 kg bag that fall beyond the purchasing power of common man. This calls for searching other cheap and better cementatious materials. In this context, Gypsum plaster/gypsum plaster blocks is the answer, that can reduce at least ten percent consumption of cement i.e. 2.5 to 3.0 million tons by introducing gypsum in building industry. This shows that at least 25 to 30 gypsum plaster plants of 1,00,000 tons/year capacity need to be set up, immediately. The demand of gypsum plaster will further increase for the construction of big and small dams as announced by the Government of Pakistan, export to Afghanistan and consumption of cement for housing. The housing backlog as given in 5 year plan (2005-2010) is 6 million units, in 2005.

BENEFITS

2. The benefits of using gypsum as a building construction material are as under:

• Energy Saver: conversion temperature of making gypsum plaster is 120 oc to 150 oc, clay bricks 900 oc and cement 1450 oc.

• Highly efficient in thermal and acoustical insulation, fire resistant, humidity controller and cost effective.

• Quick in implementation, provide steady and flat surface, dries and hardens quickly, reduces finishing work and maintenance.

• The processing technology involved in converting the raw material gypsum, into the end product gypsum plaster is simple and suitable for large, medium and small scale operations.

• The energy consumption is much less than that of alternative binding material such as cement and lime, therefore, encourages using wide variety of fuels.

APPLICATIONS:

• all non-load bearing internal partition and ceiling boards;
• all internal wall plastering to be done by using gypsum plaster; and
• to provide an introduction for development planners in government or to donor countries/agencies to the potential for increased exploitation of currently un-utilized/under utilized high quality huge gypsum deposits of Pakistan.

RAW MATERIALS:

3. Geological reports indicate potential reserves to be 4,442 million tons above surface and 472 million tons down to a dip depth of 30 meters over an area of 1,150 square kms. It has been confirmed that the composition obtained at other sites in the Kohat area, in terms of percentage of gypsum which vary from 88% to 98% designated as very high and pure. It is well suited to plaster manufacture. These deposits are also of Eocene age, crops out abundantly south and east of Kohat in a succession of anticlines and synclines.

Table-1: Location, Resources/Reserves, Quality and Accessibility of major Gypsum/Anhydrite Deposits

PRODUCTION TECHNOLOGIES

Small to Medium Scale production

4. Many developing countries have established small to medium scale gypsum plaster production plants by using variety of locally available often low grade fuels. In this context they use both direct and indirect heating methods. The methods deployed includes non-permanent and permanent kilns, open pan kilns and enclosed kilns, kettles and rotary kilns and pressure kilns or autoclaves.

Large Scale quality Gypsum Plaster Production

5. Western European countries are in a position to supply all types of plants from manual plaster factories to panel plants as well as necessary expertise. Modern kiln and associated equipment can be supplied and set up within a short period of time period (3 to 4 months) for the immediate assistance to earthquake survivors. The gypsum plaster blocks so prepared are directly useable for construction provided that gas is already available in the gypsum deposit area. In this context, gas is available at Kohat and Daudkhel areas where large and high quality gypsum deposits are available. The production capacity of typical plant is 180 or 500 tons/day and does not need any civil work. The major equipment used are jaw crushers, screens, hammer mills, worm conveyors, calcining kilns, batching mixers, moulding machines, driver, cranes, grippers, turning table etc. Most of the equipment can be manufactured in Pakistan. The drawings of the kiln as supplied by Alphaplatre of France are enclosed. Salient features of the proposed plant are as under:

Description of the Plant:

6. The kiln, manufactures from stainless steel, is of very recent design and incorporates a number of technical innovations. The kiln is a vertical type with gypsum powder feed from the top and extraction of gypsum plaster from the bottom. The feed spills over a series of cones, the centers of which are placed at the center of the kiln and which slow down the rate of fall of the gypsum powder.

7. The kiln is to operate using natural gas only which is injected through a downward facing nozzle from within the series of cones. For the hot gas to escape it has to descend to the bottom of the kiln then rise through the cones and the descending gypsum powder. The heat exchanged drives off the water of crystallization.

8. The principal innovation concerns the fact that the kiln operates under pressure of a few bars more than ordinary atmospheric pressure. For this it is supplied with a compressor that also serves to inject air for combustion. A screw system for both raw material and the fired product serve to maintain pressure in the kiln.

9. The manufacturers claim that very high quality gypsum plaster can be produced that can often meet ceramic moulding quality. This is because under slightly higher pressure a small proportion of about 15% alpha plaster is produced along with the beta plaster, enhancing the hardness characteristics. The kilns have a rated production capacity of 150 to 180 tons per day. For a 100,000 t/year plant 2 kilns are required. The kiln is delivered pre-assembled, its installation connection and starting up are carried out in 2 weeks. Moulding machine can be fitted directly under the kiln outlet. The gas consumption is about 223 kw/ton of plaster.

TESTING FACILITIES:

10. All testing facilities regarding recognizing gypsum, testing gypsum plaster (consistency, freedom from coarse particles, bending or transverse strength, mechanical resistance, setting time, expansion on setting, soundness, chemical tests etc) are available in the country.

SITUATION ANALYSIS

11. Fortunately Pakistan is blessed with huge, high quality gypsum deposits, natural gas and utilities, Chemicals used for the acceleration or retardation of setting process of gypsum plaster and rockwool as insulating material are also available. Further most of the equipment except kiln and drier can be manufactured in Pakistan.

NEXT STEP

This is the first of its kind plant in Pakistan and its implementation has to be initiated with caution. Matters of crucial importance are:

• Construction of dependable plant;
• Sufficient implementation of management and operation knowledge; and
• Establishment of marketing channels.

This calls for involvement of many disciplines. However, initially the following disciplines may be involved:

• Geology and Mining.
• Processing and quality control.
• Mechanical Engineering and Fabrication.
• Architects and Structural Engineers.
• Marketing and Financial Analysts.
• Equipment supplier (foreign) and foreign consultants.