Holcim Mexico, the second largest cement producer in the country, increased the use of solid and liquid AFRs at one of its facilities, but the change led to spillage and carryback that resulted in equipment failures, cleanup and significant maintenance costs. Martin Engineering Mexico was approached for a solution, and has managed to significantly decrease the amount of spillage, increased workplace safety and lowered the cost of operation.
The Planta Macuspana facility is located in southeastern Mexico and produces 1 million tpy of cement. Delivered in both solid and liquid forms on seven 40-inch-wide (102 cm) conveyor systems, 1.5 metric tons (1.65 tons) of solid waste and 21 metric tons (23 tons) of sludge are carried per hour to the calcinator. Solid waste products including paper, wood, plastics and shredded tires are run through a crusher and measured for caloric content (the amount of energy contained within a substance). Consisting of petroleum slurry and contaminated water, the liquid waste is mixed with sawdust and dried before also being measured for caloric content. After processing, the mix is loaded into a feed hopper, passed over a belt scale and distributed by a mechanical feed valve onto the conveyors.
The Macuspana facility used a mix of belt cleaners without tensioners and cleaning systems fabricated in-house, a combination which proved ineffective. Because the process spilled approximately 6 t of solid and liquid material a month, it needed to be monitored by a full-time employee who reported daily on spillage volume and potential hazards. Twice a month a four-person crew required a full shift of downtime to clean up piles of material and sludge from around the conveyor frame.
Following a thorough assessment of the situation, the Martin Engineering Mexico team determined that a Martin® QC1™ Cleaner PD (Performance Duty) should be installed at each of the seven conveyor discharge points. Integrated onto the existing mainframes, the units are comprised of a single urethane blade connected to a steel mandrel, which is turned by a heavy-duty spring tensioner, retaining a tight seal on the belt. The blade design utilizes patented Constant Angle Radial Pressure (CARP) technology to maintain an efficient cleaning angle throughout its service life, without damage to the belt or splice.
For applications involving belt speeds of up to 900 fpm (4.6 m/sec) and service temperatures of -40° to 160°F (-40° to 70°C), operators can choose between 5 different blade types to address the characteristics of specific kinds of cargo for each conveyor. Available in lengths of 18 to 96 inches (457 to 2438 mm), blades can also be ordered in 10-foot (3.05 meter) slugs, allowing operators to cut to length for increased versatility.
The unit features a no-tool replacement process that can be performed safely by a single worker who simply pulls the locking pin, unclamps the bracket and slides the blade out of the mainframe. The new blade is slipped on and clamped into position, significantly reducing maintenance and replacement time.
Over the next 28 days the performance of the newly installed system was monitored, with the build-up of carryback measured against that of the month prior to installation. Operators reported approximately 90% less fugitive material over the entire evaluation period, thereby significantly reducing the labour and downtime needed for cleanup.
Plant managers predict that the upgraded belt cleaning system will extend the life of idlers and other conveyor components, minimising unscheduled outages due to equipment failures. Moreover, operators confirmed that worker morale was greatly improved due to the easier cleanup and better working conditions.
Adapted from press release by Rebecca Bowden
Read the article online at: https://www.worldcement.com/the-americas/01032016/martin-engineering-mexico-reduces-carryback-601/