Manufacturing Process


	Illustration - GBT formed briquette crystal structure before calcination


	Illustration - GBT formed briquette crystal structure after calcination

As indicated in table 1, the Hi-PSI-G manufacturing process is inexpensive, easily scalable, and readily transportable. Novel methods are employed for pressing, calcining, drying, and grinding gypsum briquettes. All of the equipment used in the production process is currently “off the shelf” having been used on an ongoing basis for other applications. The process itself is simple to perform, requiring little operator input and no expensive additives. The process conditions use very little process water, minimizing energy use and avoiding water treatment costs. In addition, the drying and grinding equipment operate under conditions of ideal efficiency thus increasing production rates and minimizing energy costs.

Advantageously, GBT’s patented process provides great flexibility in the choice of raw material (calcium sulfate dihydrate) used to form the alpha hemihydrate briquettes. Material sources may include natural gypsum from mines and quarries around the world, as well as byproduct gypsum from a variety of chemical processes. Examples of chemical sources include desulfurization of flue gases, the production of titanium oxide, the production of phosphate-based fertilizers, the neutralization of waste sulfuric acid streams, or the production of organic acids and their salts, e.g., citric acid, citrates, etc.. Recycled gypsum from gypsum-based products are equally well-suited for this process.

For those plaster users that do not need to dry the excess water but require the extra strength of a low water demand plaster, e.g., floorscreed producers, the benefit is the reduced cost of manufacture, access to supplies of low cost byproduct gypsum and the ability to build small plants where needed rather than ship product from a central facility. Average production costs have been estimated at about $35 per ton, less than half the cost of a typical dry process alpha plaster and about one third the cost of a typical wet process alpha plaster. These production costs are similar to a beta plaster produced from rock.

learn about typical applications for Hi-PSI-G

Table 1 lists benefits and features of the Hi-PSI-G material and manufacturing process. Specifically, the process is able to use the advantages of both the conventional wet and dry processes without being forced to live with the disadvantages of either.

Table 1. Features of the Hi-PSI-G Manufacturing Process

Features / Benefits	Dry Process	Wet Process	GBT Hi-PSI-G Process
Water demand ml/100g	35-45	28-40	35-45
Product variability	Variable - rock	Variable - process	Consistent
Equipment cost (30,000t/yr)	Simple and low cost $15M	Specialized and expensive $25-30M	Simple and low cost $8M
Scalable equipment	Modular design	Difficult to scale up	Modular design
Production rate	Slow	Medium	Fast
Energy usage	Energy used inefficiently	More energy needed for process but efficiently used	Low energy needed, efficient usage
Operator expertise	Low	High	Low
Water treatment	None	Expensive	None
Additive costs	Possible	Expensive	None
Gypsum availability	Must use lump rock - expensive	Rock or byproducts	Rock or byproducts
Overall production cost	$75/ton	$100/ton	$35-$65/ton *
Market access – plant locations	Locations restricted by rock supply	Few expensive plants increases transport costs	Small plants using local byproducts or rock

* depends on various circumstances including facility location, available energy resources, etc.