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CAKING (Continued)
Caking (Continued)

Tracing the various samples back through the production line indicated that the adipic acid that unloaded easily was often associated with a production line that had additional cyclone fines separators and consequently contained slightly less -200- mesh particles.

The difficult-to-unload adipic acid samples always came from the line with only one cyclone fines separator and, consequently, contained more -200-mesh particles.The solution in this case was to install another cyclone fines separator.

Predict Storage Limitations

One of the many successes that Indicizer users have had is in the area of predicting and eliminating caking problems. A well-known chemical company that mines and processes one of their products in the California desert had for years been struggling with rail car unloading due to extreme caking.

They were confident that their product was flowing well when it was initially loaded onto the rail cars, but was often difficult or even impossible to unload at their customers� plants. Sometimes even rejected completely upon arrival by the buyer.

What was happening in the weeks and sometimes only days that the product sat in the Hopper bottomed containers was moisture migration. When a material contains moisture and is subjected to changes in temperature, the water molecules tend to move and form new bonds within the material. In this case, the product was loaded into a rail car immediately after production, often to sit in the rail container for weeks waiting for the final approval for delivery to their customer. During the day, the temperature in the rail car sometimes reached 130�F. Then, at night, the cool desert temperatures would often drop to near 50�F. This dramatic swing in temperature, day in and day out, can cause even small amounts of moisture within a material to migrate out toward the walls, continually reforming bonds until a material is left almost as one large hard mass. It had been found that after even just days of storage and a mere 100 miles of transport the product would arrive so hard that not only would it not flow out of the opened hopper bottomed cars, but had to sometimes be jack hammered or hydraulically blasted out.

The chemical company suspected that storage time and temperature were involved but had no way of knowing how much or how to measure it.

After some preliminary testing with the Johanson Temp Cycle Hang Up Indicizer, a customized user-defined test was set up on which the Indicizer would replicate the temperature and day/night cycling at an accelerated rate to measure how fast the product gained strength.

It was soon determined that the average production run could sit no longer than 3 days before delivery and unloading. Because flow characteristics varied from batch to batch, continuous post production batch testing was implemented to confirm storage limitations of each run.