I just returned from MINExpo in Las Vegas where a record 36,000 visitors and 1,300 exhibitors spent three days buying and selling the equipment that digs and processes the raw materials that feed our bulk materials industries. Attendance was up more than 50 percent over the previous show and exhibit space at 600,000 sq. ft. was up 30 percent.
 
This is an industry of big machines and huge capital investments, and MINExpo, which like the Olympics occurs just once every four years, brings an impressive array of equipment under one roof. Caterpillar set the mark as biggest of the big in terms of booth size and probably for the size of their machines on display here. Their big 797F and 795F AC mining trucks, standing as tall as three story houses, drew the most attention and more photographers than the fabled Las Vegas strip.

Lines of visitors snaked up the stairs to sit in the driver's seats. On a mezzanine connecting the stairs to one of the truck cabs, two training simulators let visitors test their skills at driving these monsters.

There were quite a few material handling equipment manufacturers at the show. Next to the Caterpillar booth, Gundlach was showing its 2050S Roll Crusher. Together with Gundlach's Cage Paktor, these machines have played an important role in helping a number of Canadian mines meet the booming demand for potash. Canada's remarkable growth in potash production has been driven by agriculture's increased demand for fertilizer to feed the frenzy for biofuels in markets around the world.

The flooding of a major Russian mine pushed demand for Canadian potash even higher. Russia, Canada and Belarus account for 85 percent of known potash reserves. Canada alone has half of all reserves. Russia had been the major supplier of China, and the Russian mine closing came at a time when China's demand for fertilizer was growing at more than 12 percent per year. Flooding is common problem for potash mines, and Russian potash mining is expected to return soon, giving equipment makers an opportunity for another surge in orders from the potash industry.

Coal has seen a resurgence with today's growing energy demands, and coal mining had a major presence at the show. Pennsylvania Crusher showed its Mountaineer Sizer. The Mountaineer Sizer is designed for primary or secondary sizing of coals, industrial minerals, and ores with minimum fines generation.

Penn Crusher shared exhibit space with its sister company Jeffrey Rader, which showed its NF Electromechanical Vibrating Feeder. This feeder is designed specifically for the material handling needs of the coal industry, so that burden doesn't dampen vibration and actually boosts performance. These sub-resonant tuning characteristics assure efficient material transfer, promote quieter operation, and reduce energy and maintenance costs.

Eriez marketing communications manager Keith Jones told me the top attraction at their booth was their magnetic separator for the coal industry and minerals processing. Eriez Suspended Electromagnets (SE) remove damaging tramp iron from materials conveyed in heavy burden depths on flat conveyors or chutes. They automatically remove tramp iron from heavy product flows such as coal or rock being conveyed on belts, vibratory feeders or chutes. When designed with a continuously rotating belt, these magnets are self-cleaning.

Series 6000 Suspended Permanent (SP) Magnets automatically remove large amounts of ferrous from nonferrous materials conveyed in heavy burden depths, on almost any type of conveyor or chute. These magnets require no power source, operate practically maintenance free, offer uninterrupted magnetic protection and can be installed quickly and easily.

Jones said the SP Magnets from Eriez offer a level of performance that was previously available only with electro magnets. Permanent mag¬nets designed just a few years ago don't achieve near the performance of this new line, he said.

Don Dunnington
Moderator

Hurricane Ike's recent unwelcome visit to our Gulf Coast calls to mind a friendlier "Ike," Dwight David Eisenhower, who was widely admired in the U.S. and around the world for his leadership in WWII and then as a U.S. President. I recently spent a few moments outside his boyhood home in Abilene, Kansas.

As soon as we completed our review of the new Premier Pneumatics website at their home office in Salina, Kansas, I got on the road for a three hour drive to Kansas City, from where I would fly home the next morning. About 30 minutes into my drive on I-70, I came to the exit for Abilene and a sign pointing to the Dwight D. Eisenhower Presidential Library.

It was 6:30, and I figured the library would be closed (it was). But I got this picture of Eisenhower's boyhood home. In the background to the left of the house you may be able to see railcars (shown larger here).

The Eisenhower grounds cover several acres, but in Kansas you're seldom far from train tracks. Premier got its start in pneumatic conveying with its railcar loaders and unloaders. From loading and unloading railcars, it was a short hop inside the factories to vacuum and pressure conveying solutions for a wide range of applications for the plastics, plastics compounding, food, pharmaceutical and chemical process industries.

For a few boom years Abilene intersected the western terminus of the Kansas Pacific (now Union Pacific) railroad and the end point of the famous Chisholm Trail. From 1867 to 1872, cowboys drove some three million head of cattle along this 1,000 mile trail from Texas to Abilene, where they were shipped to eastern markets. Until lawmen like Wild Bill Hickok tamed the town, Abilene was known as the wildest town in the Wild West.

From trails to railroads and highways the movement of food and bulk materials across the country played a large role in the colorful history of Kansas. And material handling continues as a major presence among the businesses and industries that came out of Kansas.

Today Premier Pneumatics is a global provider of pneumatic conveying systems. Their bulk unloading and storage systems are used in truck and railcar loading and unloading.

Premier's development of complex vacuum and pressure conveying systems has lead to an incredible array of pneumatic conveying components from their popular airlock rotary valves to vacuum sequencing receivers, self-contained loaders, bin vents, diverter valves, and storage tanks.

And it all started with a railroad that crossed Kansas.

Don Dunnington
Moderator

The Cause

The “Melfi Elbow” Solution

Ever had a problem getting powders or other bulk solids to flow out of a bin or silo?  Sure, it's a common enough problem.  Material flow problems can create major headaches and cost your company in lost production, increased labor and maintenance as well as opportunity losses associated with diminished throughput.  In addition, you can have lost product due to caking and even vessel failures as a result of flow problems.  This all means lost money, profit, etc.  That's why it's important.

The Cause
When powders are placed in a bin or storage silo it enters the vessel in a 2-phase form as a mixture of particulate and air.  Often powders are conveyed pneumatically, introducing additional air.  Flow problems will occur as the air entrained in the 2-phase mixture is expelled and the particulate packs together.  The degree of flow problem can be dependent on many factors including the material agglomeration factors and coefficients of friction.

Once entrained air escapes and the powder packs, a number of conditions can be created.  These include ratholing, bridging and flooding problems.  The illustrations here show what a rathole or bridge may look like.  Flooding is uncontrollable material flow, usually resulting from a collapsing rathole.

Solutions
Like many other things, there is "more than one way to skin the cat" (where did that expression come from?..... click here to find out ).  First, and most obvious to me is to eliminate the cause with something you can control, and do it before you have a problem.  What I am getting at is the bin or silo design.  Jennike & Johansen are experts in this field so I'll let them do the talk and just provide a link to a PDF document for more information on mass flow bin/silo design.  But don't wait until you have a problem to solve.  Consider this before you decide on what silo to buy and use.

However, most problems are existing which means the bin/silo is already in place and you can't get the powder out properly.  You need a solution quickly.  The next alternative, and not necessarily the best, is to use an external source of vibration to shake everything up so the material flows.  Does this work?  Yes, but....... it can create problems too.  Vibrators (Cougar, NAVCO, VIBCO and others) can actually pack the material by shaking it and removing remaining air.  Vibrators are typically only used when the flow of material is required.  The selection and application of an appropriate vibrator should be carefully considered and reputable companies should be consulted.

Another solution is the use of aeration devices to fluidize the powder (adding air) creating a flowable state, thereby initiating material flow.  There is a wide variety of aerating devices that come in all shapes and sizes.  The proper selection, quantity and location must be done based on experience in order to produce the desired results.  Aerating devices add entrained air back into the material creating the natural 2-phase mixture allowing it to flow.  This is successfully used on many types of powders and the aerating device itself is relatively inexpensive ($15 and up per each).  Multiple aerators will be required.  The aerators are typically in operation full time, unlike vibrators.  One example is a cement silo where 8-12 aerators are used in the cone section to promote material flow.  Each of these aerators cost about $20.  In addition, dry plant air is required along with all of the piping.  For more information on using bin aeration devices to solve flow problems, click on the image to the left.


Joe Lewis
Vice President - Marketing & Sales
Monitor Technologies LLC
jlewis@monitortech.com
www.monitortech.com
www.flexar.info

Hurricane Katrina forced my friend Steve O’Keefe to evacuate New Orleans, but thanks to local blogs he has been able to keep up with what’s happening in New Orleans right down to the neighborhood level. He also made his own urgent calls here on how to help those left behind. In both cases, we see individuals using blogs to create ad hoc communication channels that provide vital information and perhaps help save lives.

This is an example of how Blogs and other Internet technologies, such as websites and email, are facilitating the growth and speed of networked social feedback loops. Such feedback loops are not new, but their numbers and power have been multiplied and amplified by the Internet and other electronic media.

To appreciate the power of feedback loops, it’s useful to look at its application to feeding technology. Accurate feeder control depends on the microprocessor and its ability to process timely data from a feedback loop on what’s happening as the feeder discharges.

A Brief Explanation of Feeders and Feedback Loops
You can think of feeders as automation’s alternative to a scoop or shovel. A feeder delivers bulk material (usually dry, though liquids are also fed) into a process. It’s a feeder, not a scoop, that puts the two scoops of raisons into your breakfast cereal.

Volumetric feeders are the simplest type of industrial feeder. As the name implies, they measure material by volume. Most use a screw or auger to deliver the material into the process. An open loop control on a volumetric feeder provides no feedback as to how the feeder is performing. You're feeding blind and have no way of knowing (short of watching it) whether the feeder is running at all. A closed loop control tells us only whether the feeder motor is running at the speed we expected. It does not tell us if material is actually being delivered into the process, nor does it tell if the amount of material delivered is exactly what we wanted.

Gravimetric feeders, such as loss in weight or weigh belt feeders, tell us how much material was actually delivered by weight. Since weight is a more accurate measure than volume, the feedback information is more reliable than what can be expected from a volumetric feeder. Since the weight feedback is fast, as well as accurate, it is also possible for the controller to adjust the feed rate on the fly to makeup for variations in bulk density. This ability to monitor and adjust continuously is essential to producing many modern materials, ranging from high-tech plastics to life-saving pharmaceuticals.

Social Feedback Loops
Consider now, the feedback loops found in the business, economic and political arenas--the social feedback that keeps an organization or a society on track. In business, price and profits are the main signals that keep companies in business. In economics, we’ve seen that--despite its apparent chaos--a free market works better in the long run than a command economy because the market has more information and more accurate feedback mechanisms. In government--for all its apparent inefficiency and noise--democracy governs best because it is structured to seek and respond to the flow of information from a diverse public.

Feedback Is Important to Industry and Society
In industry, we see that feedback keeps a process on track so it achieves its targeted outcome. For those tasked with designing industrial control technology, the microprocessor was a liberating force that allowed a precision in machine and process control that simply wasn't possible with mechanical controls.

Today, it's remarkable to see how closely computer-aided human interactions have begun to parallel earlier developments in computer-aided machine interactions. That is, the networked computer has greatly expanded and enhanced the ability and ease with which we can give, receive and process feedback of a social nature. One of the more promising aspects of the blog is its power as a feedback loop.

Don Dunnington