Summary:Raymond mill, also known as Hanging Roller mill, is a popular grinding mill in the processing of non-metallic ore. So do you know the history about Raymond mill? Let's take a look!

Raymond mill, also known as Hanging Roller mill, is a popular grinding mill in the processing of non-metallic ore. So do you know the history about Raymond mill? Let's take a look!

Raymond mill
Raymond mill
Raymond mill

1.Who invented Raymond mill?

In 1906, C.V.Grueber established the Curt Von Grueber machinery factory in the southern suburbs of Berlin. He used his patent got in American to produce the first Maxecon mill which used as a coal grinding for the MOABIT power station at BEWAG (an area in Berlin). The capacity of this grinding mill could reach 5 tons an hour, which were sold nearly 600 in a few years. These machines were applied to different grinding field.

Finally, E.C.Loesche, a stockholder in the Curt Von Grueber, decided to purchase American patent for Raymond centrifugal ring roller mill and produced the first generation of Raymond mill when he was in charge of the Curt Von Grueber.

This kind of Raymond mill was only suitable coal materials with soft, low ash and good grinding property, because the grinding force (centrifugal force) of Raymond coal grinding mill was limited by the diameter and rotation speed of grinding roller at that time. However, German coal was characteristic of hard and high ash content, which required higher grinding power. Therefore, Raymond mill of this structure wasn’t prevalent in Germany as itwas difficult to meet the grinding requirements. But it was surprising that this kind of Raymond mill was just suitable for the coal quality in the United States, there was no doubt that Raymond mill was widely promoted and applied in the United States.

2.Who improved Raymond mill?

In 1925,E.C.Loesche summarized the use characteristics and disadvantages of the first generation of Raymond coal mill and decided to further improve the structure of Raymond mill. He developed a mill whose grinding principle is opposite to the first one, which was called improved Raymond mill.

The ventilation of this improved Raymond mill system has two modes: positive pressure and negative pressure direct blowing. The patent of this type of Raymond mill was soon acquired by Combustion Engineering (a company in America).

The Raymond mill upgraded were still problems on its roller so far. Although the roller diameter increased slightly, it didn’t work very well.

Later, Combustion Engineering developed a new generation of Raymond mill on the ground, which named VR mill.

The structure of this Raymond mill was similar in many aspects to that of the current Loesche mill. However, it was different from Loesche mill on its cylindrical grinding roller and grinder table with a 15 degree sloping surface. The grinding roller was equipped with a roll-out device for inspection and maintenance. And it also equipped a protective device to prevent metal contact between the grinding roller and the grinding table. In addition, the grinding roller can be lifted in advance before the mill starts that can reduce the pull-in torque.

Raymond mills were usually used to make pulverized coal in the United States. The fineness of finished product varies between 250-325 mesh (fineness and output can be adjusted during operation).

With the development and improvement over the years, there are more and more types of Raymond mills. Since China introduced this machine, Raymond mill has been well received by majority of users due to its high stability, well-adapted and highly cost-effective. So we can see that Raymond mill plays an important role in grinding equipment.