Formed solid sulphur - the market criticality of quality

[By our guest columnist, 'Thiophilos']

Far from being a new topic of conversation, the quality of the various types of formed solid elemental sulphur available on today’s world markets nonetheless remains an important one for a variety of reasons. We live with a market that varies from boom to bust in a short few months, as was seen a couple of years ago. Predictions are for massive oversupply as energy producers drill into higher sulphur content sources of hydrocarbons. Surely competitive advantages such as product quality remain important factors in determining whether your product sells or doesn’t – and how much it sells for?

It used to be that when the market talked quality with respect to bulk solid sulphur it was chemical purity that was in mind; what was the ‘ash’ content? - meaning all the contaminant minerals present that shouldn’t be, or what was the ‘carbon’ content? - focusing on how much hydrocarbon had found its way into the not so bright yellow sulphur for sale. Or trace quantities of arsenic, selenium and tellurium (AST) that weren’t popular with the fertilizer manufacturers that converted it into sulphuric acid for phosphate production. And even the moisture content - great for keeping dust emissions down during handling and transportation but bad news for wet sulphur corrosion of iron-containing vessels that stored or transported the stuff, like marine bulk carriers. And there are more quality offending chemicals on the impurity list.

These impurities are still on the buyers ‘no-no’ list, or at least are reasons for substantial discounts to whatever the market price may be at the time. But with 50 million plus tons of the stuff moving annually through world transportation systems, another important quality feature has emerged in the solid formed version of the yellow element - its physical handling and storage characteristics. How does it respond to rough handling in bulk? Does it crush easily? Do such properties change with time in storage – the ageing process? Is it a big generator of fugitive dust emissions? Are these emissions hazardous with respect to fires, explosions or environmental impact? It is a whole new ball game as far as what is meant by quality of product.

Is this more recent emergence of a different set of quality factors for bulk formed solid elemental sulphur a valid development? It is hardly a new development. For many decades in the twentieth century it was one of the strong arguments in favour of storing and moving elemental sulphur in its liquid form. But this was in the days when sulphur was mined (Frasch) to meet market demand, not as an involuntary by-product of hydrocarbon oil refining. The buyers in those days were also well equipped to receive and handle the hot liquid product, more so than many of today’s developing countries, who import the stuff to make the acid to produce the fertilizer to feed the billions. All this on top of the specialised nature of the heated tankers needed to haul the molten sulphur half way around the world.
So what are the driving forces behind the inclusion of physical handling and storage characteristics in the Quality Factor? From a public relations and social responsibility standpoint it must surely be environmental impact. There is little doubt that if the handling of formed solid elemental sulphur generates significant quantities of fugitive dust particulates, it is hazardous on at least two counts; first the potential for fires and explosions, with all the implied safety and insurance consequences; and second, the ease of aerobic oxidation of the dust to form acid (rain) with all of its negative effects on green and growing matter – animal and vegetable and even mineral.

So what have we been doing about responding to this quality challenge for formed solid elemental sulphur? Quite a lot. A generation ago a whole bunch of world trade solid sulphur was still being moved and stored in what was called “crushed bulk” form. Many of today’s dealers in bulk sulphur are probably too young to recall the fugitive emissions from a windblown pile of crushed bulk sulphur being pushed by a bulldozer or conveyor loaded to railcar or marine bulk carrier, but it was an activity with lots of environmental impact! The era of development of higher quality formed solid sulphur began first with slate or flake, then the various wet forms that led to the granules, pastilles and prills that came to be labelled as the Premium Product that we see more and more on today’s world markets.

But just as the quality of the formed solid sulphur product has risen on the environmental and safety scales, so also have the demands of the global jurisdictions into which the bulk solid sulphur is sold. Fine particulate emissions of sulphur oxidise to acid more quickly, corrode metals more aggressively, threaten lung damage for those who breathe it and tend to burn or explode with a bigger bang. None of the above are deemed acceptable in 21st century commodity businesses. The closer we approach the 100% containment goal, the more the best and most willing buyers demand even better efforts to be really safe and environmentally friendly.

So the message is clear: the solid sulphur industry deserves credit for its work to date but, in this era of ever-increasing competition for a place in the market , the buyers are exercising their long established right to demand the best Quality for the least cost, and achieving that goal is an ever-present challenge for the solid sulphur forming industry.
‘Thiophilos’