The office is that last door on the right before you reach the factory floor. It’s 10 degrees hotter than the rest of the building because one wall is made entirely of glass and faces the setting sun. Inside sits a guy who looks fairly normal except that he’s 6’2” and built like a linebacker. He talks like everyone else, smiles like everyone else, and drinks Diet Coke like everyone else. But don’t let him fool you.

Tim Gunn is an alchemist.

In cased you forgot your ninth grade world history, alchemists were those weird chemists who thought they could turn dirt into gold. They couldn’t. Tim Gunn can.

OK. So maybe Tim doesn’t turn dirt into gold through special chemical forces that he learned from the dark monks of the Himalayas. He does take dirt and pull gold out of it though.

The Magic Mixer

Tim came up with the idea for the mixer that could take dirt and turn it into gold when Johnson Mathey called and said they had a problem.

Johnson Matthey is a billion dollar chemical and precious metals company. That means they dig for gold. When they dig for gold, they create dust. In that dust, called fused agglomerates, are little pieces of gold. The company then takes the agglomerates, puts them in a container with acid, and lets the acid eat off the dirt until all that’s left is gold. It’s not turning dust into gold, but it is pretty close.

The problem was their mixer wasn’t working. They put the dust in the tank, poured in the acid, flipped the switch and nothing happened. The acid moved around, but the dirt just stayed on the bottom of the tank.

Enter Tim wagging the Dikembe “No no” finger.


dikembe-mutombo-geico-commercial Source:

Tim recognized that the mixer that Johnson Matthey was working with was using an axial flow turbine. When they rotate, axial flow turbines send force down, to the left, and to the right. There wasn’t enough force hitting the dust to make it move. Tim recognized that in order to get those little pieces of dust floating in the acid solution, we need to thrust the solution downward into the dust which would force the dust to the edge of the tank and then up the side walls into the acid. The idea is used in what’s called “solid suspension applications.” The idea is that a solid needs to be suspended in whatever substance the solid is in. In this case the dust needed to be suspended in the liquid acid for the chemicals to have enough time to work on the dust. If the dust settled back down on the bottom of the tank, then the chemicals wouldn’t be able to do their job.

In order to improve thrust to get the particles higher into the solution to give the acid more time to work on the dust, Tim recognized Johnson Matthey needed a higher bulk velocity than what the axial flow turbine was able to achieve. Tim suggests that we use a hydrofoil turbine. The increased angle of the hydrofoils blades forces the liquid down at a higher velocity. The higher velocity would send the lazy little dust particles on the bottom of the tank up into the acid above continuously. The idea was that the dust would never settle back to the bottom of the tank as long as the mixer was running.


Axial flow An axial flow turbine



Hydrofoil A hydrofoil impeller


TFLXXXXXX Flange Mount Mixer with Hydrofoil

Not only did the hydrofoil impeller mean that the solution would get more thrust, it also meant that the process of mixing would be easier on the whole system. The mixer wouldn’t need as large a motor as an axial flow turbine because the hydrofoil could create the right amount of thrust with less power. Because the motor was smaller, the gearbox could be smaller. Because the gearbox could be smaller, the shaft could be smaller. Essentially, Tim thought up an idea that would not only make the mixer work appropriately, his idea was going to make the whole system cheaper.

However, we ran into another small problem. The guys at Johnson Matthey didn’t want to spend anymore money on a tank that “should” work. They wanted something that would definitely work. They can’t send us the dust because it’s considered a hazardous material, so we can’t test it here. We don’t want to build the full mixer and then have them send it back. So we reached an impasse, right?


Tim, in his infinite wisdom, says, “No problem.”

He rigs up a miniature version, called a bench top mixer, and send it on for them to test it out. When they got it, they put the dust in, poured in the acid and flipped the switch. And, as if you haven’t guessed at this point, it worked.

Since that time Tim and the other engineers at Mixer Direct have come up with lots of other solutions for people who have solid suspension mixing needs. No, they aren’t magical chemists. They’re just guys who understand problems and know how to get the right solutions.

I really think the prophet Vanilla Ice may have been speaking of Tim Gunn when he said, “If there was a problem, yo, he’ll solve it. Check out the mixture while impellers revolve it.”