Point Comfort Operations -- Overview
Point Comfort Operations is located on the Gulf Coast of Texas and is part of the US Primary Products System. The Operations include a 3,000 acre Refinery and a C-30 Hydrate facility.
Point Comfort’s chief product is alumina for aluminum and alumina-based chemicals.The majority of the alumina produced at Point Comfort is Aluminum Grade and is shipped by barge and rail to plants that produce aluminum.
In 1948, Alcoa started manufacturing activities in Calhoun County, Texas with the construction of the first aluminum production facility powered by natural gas. The initial plant, a three-potline aluminum smelter, was completed in 1950 and later expanded to seven potlines. An alumina refining plant started operations in 1959, and facilities producing cryolite, lime, aluminum fluoride, caustic, and chlorine were also added in the 1960s. In 1980, Alcoa discontinued aluminum production at Point Comfort Operations.
Each month sees the arrival of several ships carrying bauxite from the West African nation of Guinea or from other regions in the Caribbean or South America. It takes several days for the cranes to unload an average ship, which contains about 50,000 metric tonnes of bauxite.
The Alumina Refinery
The Alumina Plant has the rated capacity to produce 2.3 million mtpy through the Bayer Process. The bauxite that Alcoa uses yields about one metric tonne of alumina for every two tonnes of bauxite. Once off the ships, the bauxite is stored where bulldozers can blend the various grades of bauxite before it enters the refining process. The Bayer refining process, used by alumina refineries worldwide, involves four steps – digestion, clarification, precipitation and calcination – to extract alumina, the necessary feedstock for our aluminium smelters.
The Bayer Process dates back to 1888 and was developed by an Austrian chemist named, Dr. Karl Josef Bayer. Point Comfort Operations is a “double digest” six-digester unit plant using the traditional Bayer process.
At Point Comfort, alumina is separated from the other constituents of bauxite by first crushing the bauxite and then mixing it with a hot solution of caustic (sodium hydroxide). This step of the process occurs in large pressure tanks called digesters.
Point Comfort uses two digester cycles to maximize the recovery of alumina from the bauxite. In the digester, the caustic dissolves the alumina in the bauxite to form sodium aluminate.
Insolubles, such as sand and mud, are settled and filtered out, leaving a solution of dissolved alumina hydrate. The liquor from Clarification must be cooled prior to crystallizing the alumina dissolved in the digesters. This is done in the Heat Interchange Process.
Precipitation starts when the alumina-laden liquor is pumped into tanks that are more than five stories high and 24 feet in diameter. Each tank can hold nearly 200,000 gallons. There are more than 100 precipitator tanks at Point Comfort. During the Precipitation process the liquid is cooled and seed crystals are added causing the alumina to crystallize or “grow.” As the crystals grow they gradually settle out of the solution.
During the last step of the refining process, the crystals, now called “hydrate,” are filtered, washed and heated at temperatures up to 2,000 degrees Fahrenheit to remove the water. What remains is alumina, the white powder that is half aluminum and half oxygen.
The Calcination Department also produces Special Calcines and the Wet Filter Cake that is used in paper additives, china dinnerware, synthetic marble for sinks and electronic packaging.