It has been a year of little change at the Indiana Army Ammunition Plant. A few buildings have now be emptied of their contents, cleaned and prepped for eventual burning and subsequent demolition, and some more ground has been cleared of vegetation, but all in all, not much has changed. This is the second post in a series on the ammunition plant, which ended with the Ether-Mix House. This thread continues on, traversing somewhat in reverse in the powder production process with the Dehy Press House (Building 202-6) that pressed the cake of nitrocellulose into a powder form.
The Blending and Wringer House (Building 113-3) was part of the nitration process and was located a step backwards in the powder production process. In order to obtain a uniform propellant and ballistic characteristic, portions of batches that have a high nitrogen content are mixed with portions that have a low nitrogen content. Slurry from the poaching tubs in the Poaching House were fed onto vibrating screens where nitrocellulose was blended, which passed into collecting boxes. The boxes were then emptied into tubs where guncotton and pyrocellulose were blended. If the sample from the tub had satisfactory nitrogen and solubility content, the slurry was pumped into the Wringer House. At the Wringer House, the large amounts of water that were used throughout the process to move the nitrocellulose is removed. The containers of partially dry nitrocellulose are transported to the Dehydration/Press House via lag cars.
The poaching process was conducted to reduce the acidity of the nitrocellulose. It also reduced the fibers remaining to minute fragments in a mechanical operation. Hot water washes in sodium carbonate, an alkaline solution, further reduced acidity. The nitrocellulose was then bathed in cold water under mechanical agitators to purify the nitrocellulose and ensure for a longer shelf life. Samples were sent to a nearby laboratory to determine the percentage of nitrogen, the solubility of the ether-alcohol mixture and the fineness degree. The following are from the Poacher House (Building 112-3).
The Pulping House, located adjacent to the Poacher House, features machinery similar to that found in paper mills. Nitrocellulose fibers were cut into short segments to open the embedded fibers which exposed any remaining impurities in the capillary channels. During this process, a very large amount of water was used, which resulted in a slurry that was pumped into the Poaching House.
Skipping over some buildings, we made our way to the Nitrating House (Building 105-1). With shredded cotton being blown in from the Cotton Dry House, 32 pounds of cellulose fiber were mixed in stainless steel nitrators that contained 1,500 pounds of nitric and sulfuric acids that were blended together. The treated nitrocellulose and spent acids were then discharged from the bottom into centrifugal wringers that removed most of the acid through the exterior of the wringer. The acid was used in the production of pyrocellulose or fortified for reuse. Wet nitrated cotton was then immersed in water and the slurry transferred to the Boiling Tub Houses.
The Cotton Dry House (Building 104-1) is where cotton linters, or short fibers that cling to cottonseeds after the first ginning was delivered in 150 pound bales, or wood pulp delivered in rolls of 700 pounds, where they were shredded. They were then pretreated in large ovens to reduce the moisture to less than 1% before being blown in ducts to the Nitrating House.
Next door was the Warehouse (Building 101).
The Process Engineering Division (Building 706-2) has been fairly recently cleaned out.
The Sulfuric Acid Concentration Plant (Building 303-2) produced sulfuric acid by melting and burning raw sulfur, which produced sulfur dioxide gas. The gas was then passed over catalytic beds that produced sulfur trioxide gas, which was absorbed through distilled water that produced sulfuric acid.
And no visit is complete without a stop to the Power Plant (Building 401-1).
This is part two in a series on the Indiana Army Ammunition Plant.