A major phosphate production company in central Florida has reaped the benefits of GIW’s pump equipment and expertise by using dry-sump bearing assemblies on the matrix pumps that it uses to move phosphate slurry from mining locations to its production facilities. The switch to dry-sump bearings has more than doubled the life of the bearing assemblies in these heavy-duty pumps – for only about a 40-50-percent premium over conventional pillow-block bearing assemblies. Some of these dry-sump assemblies have lasted more than four years without requiring replacement.

Dry-sump vs. traditional assemblies;

GIW’s dry-sump bearing assembly design provides two main areas of innovation that extend the life of the bearing assembly over traditional designs.

First, this design uses a cartridge housing instead of a pillow-block housing. The cartridge has fewer sealing areas (two rather than the four in a pillow-block assembly), making it more maintenance friendly. The GIW design also has a non-contacting isolator seal system and a patented isolator added to the front of the assembly. The new design also allows for a stiffened shaft and limited end float improvements, further adding to the run life of the cartridge bearing assembly.

Second, the dry sump uses a pressurised or positive bearing lubrication system. This system continuously pulls the lubrication oil out of the bearing assembly, filters it and injects it back into the bearing assembly. Standard pillow-block bearing assemblies use flooded lubrication, or a static bath of oil that the bearings run in. This method can result in uneven lubrication and a buildup of particulates in the oil over time.

In the dry sump design, a 25 gallon oil reservoir sits on top of the cartridge assembly. The result is cleaner and cooler oil, which keeps the pump operating temperature as much as 20-30 degrees Fahrenheit cooler. In addition, the pressurised lubricant allows the pump to be installed in non-level locations, something that is important in the sandy, wet environs of central Florida.
Florida phosphate producers typically pump slurry from their mining locations to production facilities through pipelines ranging from one mile to 14 miles in length, with pumps set in series at separation distances of approximately one mile. Pumps are often installed on steel skids that can easily be moved as needed. Therefore, it is difficult for these pumps to be installed and remain level over time.

The hot and humid environment of central Florida means that bearing assembly operating temperature is important as well. The phosphate company has now installed four dry-sump assemblies and is in the process of upgrading all of its Matrix pumps to this new configuration as old style designs require replacing. The results have been that good.

Bearing assemblies are components that are manufactured to precision tolerances, and the assemblies have to maintain those tolerances over time to ensure long life. Any variation in oil level, cleanliness and temperature can damage the bearings and affect performance.

Typical cartridge bearing assemblies have to be installed on level ground and remain level over the operating life of the pump or the bearings will fail over time from lack of lubrication. The pressurised lubrication of the dry-sump design allows for the pump to be installed in non-level locations without harming the shaft.

Standard pillow-block bearing assemblies have an average working life of 12 months, depending on operating conditions and environment. GIW’s dry-sump designs more than double this life, with some lasting more than four years. For installations that do not require the pressurised lubrication portion of the design, the redesigned cartridge assemblies can be used on their own to improve the performance and life of the pump. The new cartridge assembly also benefits from a stiffened shaft design which reduces shaft deflection by approximately half.

The dry sump design has been successfully used in phosphate mining, but this approach could also benefit other mining sectors, such as oil sands (hydrotransport and tailings), hard rock in very remote locations and dredging.

Existing matrix pumps can easily be upgraded to the dry-sump design. Any 9-inch bearing assembly can be upgraded by company maintenance personnel. The dry sump components are standard GIW catalog items, allowing them to be procured and installed fast.

According to Jack Condon, GIW sales manager for central Florida, “Now that we have proven this dry-sump design, we anticipate all Florida phosphate companies to adopt our new technology. With approximately 400 matrix pumps installed in the phosphate industry, there exists a huge potential for improved run life using this new GIW design. It’s an easy swap for a major improvement.”

Currently there are about 400 matrix pumps being used in the phosphate industry, but so far only one customer has made the leap to the dry sump design and is reaping the benefits.