In a presentation at the ICIS African Base Oils and Lubricants Conference in Dar es Salaam, Meyer said that the closure of so many Group I refineries poses a threat to traditional bright stock production. The situation is further complicated by the shift away from Group I technology in the production of finished lubes.

Emmanuel Ekpenyong, lubricants head for HOGL Energy Ltd. in Lagos, Nigeria, agreed that the continued closure of Group I refineries will result in the exit of paraffinic bright stock from lubricant recipes worldwide. It may take a while, but it will surely happen. Worthy of note is the emergence of Group II bright stock, which is slightly lighter in viscosity but cleaner than traditional paraffinic bright stock, he said.

Cliff Classen, CEO of Orbichem South Africa, explained that another alternative is naphthenic bright stock. He noted that Ergon has developed a new process by which it can manufacture a high-viscosity naphthenic base oil that could effectively replace traditional bright stock. And HOGLs Ekpenyong added that naphthenic bright stock is anticipated to eventually be cheaper per ton than traditional paraffinic bright stock.

In terms of pricing, Classen said there is no difference between naphthenic and paraffinic bright stock. But using naphthenic bright stock could result in cost savings for blenders because it is more viscous and can be used at lower treat rates.

An added benefit is that the end product will have lower sulfur because naphthenics have extremely low sulfur content due to the refining process used, Classen said. Ekpenyong agreed that the low sulfur content in naphthenic bright stock is an advantage; however, he added that it is limited by lower kinematic viscosity.

Classen noted that one advantage of naphthenic bright stock is its very light color compared to paraffinic bright stock. Therefore, as the world moves toward clear Group II base oils, naphthenic bright stock fits in well with the profile of emerging Group II base oils. Now you have a bright stock that looks better, is lower in sulfur and has a lower treat rate, making it an attractive option for a blender, said Classen.

On the other hand, he noted that heavy naphthenic base oil is hazy and does not appeal to the industry because companies assume it contains impurities. Classen explained that appearance is an industry requirement, and a product is deemed acceptable when it is rated as bright and clear. Therefore, one attraction of naphthenic bright stock is its bright and clear appearance.

Classen acknowledged that naphthenic bright stocks have been around for some time, but older products were hazy. However, he emphasized that the new bright stock from Ergon is clear, making it acceptable to blenders.

The viscosity of the new product ranges from 950 to 1,000 centiStokes, which is fairly heavy. In contrast, the viscosity of Solvent Neutral 600 is limited, so if you wanted to blend heavy gear oil, you had to add additives. Now, he said, You can add bright stock to produce a high-viscosity product at a much lower cost.