Reagent Selection

By-product Analysis

The market is best viewed in terms of three production quantities, elemental sulfur production, power plant SO₂ emissions, and gypsum production. All of this production is graphed as equivalent sulfur.

U.S. Sulfur Production (millions of tons)

The nine million tons of domestic sulfur is already byproduct. No sulfur is mined. So this is not a market. So three million tons of sulfur which is imported is a market. 1.3 million tons of sulfur equivalent from FGD plants is already going into gypsum. This leaves four million tons of sulfur equivalent as a market for new FGD facilities. So in one sense the market available is seven million tons. But if you add in the 1.3 million already served with gypsum the total of both served and available is 8.3 million tons.

This 8.3 million tons consumed compares to total emissions of just eight million tons. Therefore the demand slightly exceeds supply. It is important to note that if all SO₂ went to gypsum wall board demand would exceed supply. Therefore conversion to sulfuric acid as a substitute for imports is logical. This thesis is further supported with an analysis by Bob Bruce of Innogyps who concludes that wall board plants will only be able to handle about four million tons of sulfur equivalent.

Another consideration is that about 15 percent of the present FGD systems cannot produce gypsum. Furthermore a number of future systems will use dry FGD and have a mix of flyash and gypsum which can only be land-filled. Assuming this is 15 percent of the eight million tons of sulfur equivalent then there is an unfilled demand of another 1,200,000 tons of sulfur equivalent.

It should also be noted that all eight million tons of sulfur emitted from the stacks will not be captured. In fact over the next 10 years only about 6 million tons/yr will be captured. This adds another equivalent of two million tons per year of unfilled demand.

A further consideration is that there may be breakthroughs which result in the production of alpha hemihydrate cement as an alternative to gypsum. The product sells for more than $250/ton. This may expand the gypsum market. There is some need for gypsum as a soil conditioner. The elimination of acid rain has resulted in sulfur deficient soils in some areas.

Sulfur Uses

The biggest use of sulfur in the U.S. is for fertilizer, followed by refineries and then metal mining.

The fact that only five percent or 600,000 tons of sulfur equivalent is used for other purposes means that for a company such as Mitsubishi, which is at the far end of the distribution chain, it is probably best to ignore specialty markets such as water treatment and ethanol. On the other hand, the fact that some of these applications due utilize dilute sulfuric acid and that the markets are big enough to take the consumption from one or two power plants means that they should not be overlooked entirely.

FGD Stack Gas Use

Unless there are breakthroughs on the creation of superior forms of gypsum it is likely that wall board consumption will only be four million tons of gypsum equivalent. On this basis about 0.8 million tons of sulfur equivalent could be converted to sulfur. This would be approximately 20,000 MW assuming that higher sulfur plants were those creating the product.