Solidifying a Solution: Why Many Producers Choose to Solidify Sulfur Byproduct

Sulfur byproduct creates both a challenge and an opportunity for oil and gas producers. If managed correctly, sulfur can be marketed and sold to a variety of industries. However, sulfur has many properties that make it challenging as it travels through the supply chain.

Meeting Regulatory Requirements through Sulfur Recovery

Sulfur recovery removes sulfur compounds from either natural gas or crude oil during refining and processing. Removing hydrogen sulfide (H2S) and sulfur dioxide (SO2) from crude oil is important for two reasons. First, sulfur recovery improves emission controls when the fuel is used for combustion. In fact, regulations require that sulfur is removed from products such as marine fuel or ultra-low-sulfur diesel. Second, before sulfur can be safely transported, it must be further reduced. European and Canadian regulations require that molten sulfur contains less than 5 or 10 ppm of H2S.

Supply Chain Considerations for Sulfur Byproduct

Hydrotreating, a catalytic chemical process, is the most common way sulfur is removed from refined petroleum products. This process leaves sulfur byproduct in a liquid or molten state. Sulfur can be sent to market in both of these states. Fertilizer manufacturers, for example, can use both liquid or solid sulfur. However, molten sulfur must be kept at a high temperature to remain viscous which can limit transportation options.

The issue is further complicated by the logistics of bringing sulfur to market. Most sulfur reclamation takes place in one part of the world while many of the fertilizer manufacturers are located elsewhere. Consequently, many producers decide that converting sulfur to a solid is a more practical option than transporting liquid sulfur across long distances.

Solidifying a Solution

There are several methods for solidifying molten sulfur: pastillation, granulation, wet prilling or blocking. Each of these options has benefits and limitations that should be explored in relation to the operational goals of the specific application.


Pastillation occurs when water is sprayed under a steel belt as liquid drops of sulfur are deposited to produce pastilles. This is a popular method because it is easy to set up and offers lower environmental risks since the water and sulfur do not come in direct contact with one another during processing. As an added benefit, the equipment can also be utilized to create additional products such as urea or sulfur bentonite.


Granulation takes place when liquid sulfur is sprayed onto a seed curtain to form sulfur particles or “seeds.” The sulfur seeds are cooled as water is sprayed into a rotating drum. This method has a high production capacity and is a great option when large quantities of sulfur need to be processed.

Wet Prilling

Wet prilling occurs when liquid sulfur is introduced at the top of a forming tank for direct counter-current heat exchange with water. The sulfur prills are removed from the bottom of the forming tank. One of the biggest benefits of wet prilling is economic efficiency. The equipment required to start prill production costs less than granulation and pastillation and this method also offers lower operating costs. Wet prilling also offers the ability to meet size and uniformity specifications set by international customers. 

Sulfur Blocking

Sulfur can also be stored in large solid blocks. Molten sulfur is transported via pipe to a blocking area where it cools and forms large blocks. This option is ideal for long-term storage. 

Whatever method best suits your plan to market and transport sulfur, care must still be taken to minimize the health and environmental risks of sulfur dust. There are many options for sulfur processing and it’s important to determine which option best meets your goals. If managed effectively, sulfur can provide an additional source of revenue while helping you meet regulatory requirements.

Sulfur Solidification Solutions from Matrix PDM Engineering
Through the acquisition of Devo USA and Houston Interests, Matrix PDM Engineering is now considered the industry leader in sulfur removal, forming and handling. Our team uses proprietary technology to convert molten sulfur into solid granules. 

In 1980, engineers carefully analyzed more than 15 different sulfur forming processes. From this in-depth investigation, they designed a wet prilling or pelletizing process. This innovative process is simple to operate and environmentally friendly. It requires little capital upfront and ongoing operational costs are minimal. 

Most importantly, this process greatly reduces the risks associated with sulfur dust. Traditional methods, like a dry process, can present a risk for fire or even explosion. However, this process virtually eliminates that risk. A small amount of moisture adheres to the surface of the pellets greatly reducing the amount of sulfur dust formed.  

Since 1980, our teams continue to build on the success of our wet pelletizing process. Our single units boast a capacity from 50 to 2,000 tonnes per day.

Sulfur Block Pouring  with Matrix
If your operational goals call for block pouring, Matrix has the leading-edge solution. The Devco Pivot Pour system uses our proprietary towers and arms configuration to evenly distribute sulfur in thin layers. This improves safety by eliminating the risk of dangerous pockets of molten sulfur.

The Matrix PDM block pouring arms are mobile and more efficient than their traditional counterparts with cantilevered block pouring units. Each arm can pour more than 3,000 tonnes per day over an incredibly large surface area, thus creating thin layers for added safety. Matrix pouring towers can be designed to accommodate a wide range of sulfur block pouring configurations and are easily erected on site. Our mobile arms improve safety and your bottom line. Matrix towers and arms require significantly less capital to design and install than many other options.

Sulfur-Extended Asphalt
Perhaps one of the most exciting innovations is our technology that uses sulfur with a proprietary additive to improve roads. Devco partnered with Rock Binders Inc. to develop technology to build better roads. Devco’s Bay Sulfur Company was the first facility in the world to produce SEAM® (Sulfur Extended Asphalt Modifier) using the standard wet sulfur pelletizing process. 

Special proprietary substances combine with sulfur at conventional asphalt batch plants for odor-free blending. SEAM strengthens asphalt pavement while virtually eliminating rutting and cracking.

Learn more about sulfur-extended asphalt here.

Solid Solutions from Matrix PDM
As you can see, there are many advantages to solidifying sulfur. Our team can help with sulfur forming, facility design, long-term storage solutions with sulfur blocking and sulfur melting. Whatever your goals, we can provide a solution with our conceptual engineering and operational expertise. 

Contact us today to find out what sulfur solution might work for you.