Introduction
Rotary equipment can be used in a variety of minerals processing applications, including the production of aluminum, coal, iron ore, oil sands, sand and gravel, and many others.
This equipment is characterized by a rotating cylinder or drum that rests on a trunnion roller base. It can be used for breaking large lumps of ROM material into beltable pieces, for screening out unwanted materials and oversize, and for scrubbing contaminants from sound ore.
Two main types of rotary equipment include Rotary Breakers and Rotary Scrubbers.
Rotary Breakers
Rotary Breakers are used for material size reduction, particularly in coal applications, as well as for scalping off undesirable material at the same time. The cylinder contains internal bars that continually lift and drop the material onto internal breaker plates as it rotates. This lifting and dropping, along with the material-on-material interaction, causes the material to break along its naturally occurring fracture lines into smaller pieces.
Rotary Scrubbers
Rotary Scrubbers are used to remove deleterious material from sound ore. Water is mixed with the feed and enters the drum, which like Rotary Breakers, contains internal lifters that continuously lift and drop the material to break down soluble contaminants.
With the addition of a screening section, Rotary Scrubbers can also be used to perform material sizing and separation.
Rotary equipment is known for being able to handle large feed sizes and process high capacities. This, coupled with industry demand for minerals globally, allows for these machines to be of massive size.
For example, the largest Rotary Wet Screen
McLanahan has ever manufactured was built for the power industry in the
mid-2010s. It was designed to process 9,204 tons per hour (8,350 mtph).
The Rotary Wet Screen weighed more than 1.6 million pounds (more than
725 metric tons) and measured 106’ (32m) long, 43’ (13m) wide and 26’
(8m) high. It took approximately 20,000 man hours to fabricate and build
this massive machine and then 45 truckloads to deliver it to the
customer.
“It was the largest piece of equipment we’ve ever built here at McLanahan,” explained Tyler Piper, Global Director of Engineering. “A lot went into that to make it a successful project for McLanahan.”
While that was the largest piece of rotary equipment McLanahan has ever manufactured, there have been many others of slightly smaller size that are no less impressive. McLanahan is well equipped to build these rotary beasts, with facilities and equipment designed for fabricating these giants, as well as highly trained personnel to engineer and manufacture them.
Getting Started
Although rotary equipment can of impressive size, the same approach is taken regardless of if it is a pilot plant or the largest machine McLanahan has ever built.
The process of manufacturing rotary equipment begins with engineering the design. The first step is to determine the size of the equipment.
Rotary equipment is sized based on the following information:
- What type of material is being processed?
- What are the characteristics of this material? Is it wet or sticky? Does it contain clays, organics or other deleterious material?
- What is the largest particle size in the feed that the equipment must be designed to handle?
- What throughput does the customer require?
- How much retention time is needed?
- What type of product does the customer need to produce?
Additionally, engineers need to know what is required of the rotary equipment.
- Is it intended for washing or material size reduction?
- Will it need to perform material size separation?
- Does it need to be a combination of any of these?
From this information, the engineering team is able to select the
correct rotary equipment for the application. Once the size of the
equipment is determined, the drive package, bearings and tire size can
be selected, and the engineering team can really start to look at the
details in the design.
Other considerations that go into designing rotary equipment include factors that could affect the selection of drive components or electrical equipment. For example, the operating environment. Is the climate hot or cold? Predominantly wet or dry? Tropical, desert or marine?
“Most of our rotary equipment lines are tailored to the specific application to meet our customers’ needs,” said Piper. “We have standard bearings and trunnion sizes and tire sizes, but the internal workings of the cylinder itself – the liner package, lifters, screen plates – that is all tailored specifically to the application to maximize production for our customers.”
The Process
Once the design has been finalized and approved with engineering and
the customer, it is released for manufacturing. This process involves a
combination of state-of-art equipment and technical personnel who build
the production schedule; procure resources; machine, weld, fabricate and
paint the individual components; and finally assemble the individual
components according to the engineering drawing. Some of the assembly
involves installing the screening sections and lifters to the cylinder
frame and heat-treating the drum ends at high temperatures to fit the
tires that rest on the trunnion base.
“As far as the welding goes, everything’s really heavy and really thick,” said Fabricator Welder Matt Ball. “It takes a lot of time and a lot of effort and a lot of weld wire and a lot of hands-on from everyone involved. It’s a lot of work, but it’s good work. The welding aspect is really crucial. Everything has to be precise.”
Precision, Precision, Precision
As Ball said, precision is extremely important when it comes to manufacturing rotary equipment. Components have to be machined within thousands of an inch so that the rotary equipment is able to operate as intended.
“I think that’s one of the best things that I like about it is the precision,” said Senior Field Service Technician Denny Glunt. “It has to be very precise and spot on.”
Glunt said that the precision aspect can be a challenge, but one the McLanahan team embraces and is very good at.
“We have a great team, and we have a lot of back up with engineering, and we come up with some very clever ways of doing things,” Glunt said. “We’ve been doing this a long time, and we’re very good at what we do.”
Teamwork
Perhaps the most important aspect of manufacturing rotary equipment is teamwork. The sales and engineering teams work closely with the manufacturing department, which includes everyone from machinists and welders to fabricators and painters, to ensure the build is executed according to design.
Not only is teamwork necessary to ensure the equipment is built correctly and with precise alignment, but it is also necessary for safety. When working on equipment of this scale, assembling components that are bigger and weigh more than the people working with them, teamwork is imperative.
“There can’t be any mistakes made,” said Ball. “Everything’s heavy. Everything’s huge. It takes everybody working together and watching out for each other to really make sure everything goes smoothly and nobody gets hurt.”
Testing
After the rotary equipment has been assembled, it undergoes strict testing to ensure performance and reliability. Various tests measure everything from vibration to bearing temperature to alignment – all to ensure design performance.
“The point of the test run is to make sure that we’re happy with what we’ve built, and we want the customer to be happy when they receive the product,” Piper shared.
The End Result
Once the rotary equipment has passed the testing phase and the team
is happy with the performance, Ball said it’s pretty much all hands on
deck for loading the equipment for shipment to the customer. McLanahan
then provides installation and commissioning support on site to get the
rotary equipment into operation.
McLanahan has produced rotary equipment of many different sizes for many different aggregate and mineral applications around the world. McLanahan rotary equipment operates in some of the harshest of conditions and in some of the remotest regions.
“Each piece of equipment that we design for our rotary equipment is designed specifically for that application,” Piper said. “As far as our designs, they’re very rugged and they’re built to last. And they do.”
