Dear Mr. Farooq,

Before anserwing, confirm information:

1. Flow rate given @ 20 t/h

2. Material bulk density

3. Size distribution (noting your range 20mm down to 50 mesh)

4. % surface moisture (noting 5% - is this surface, inherent, both)

5. Location: seaside or arrid - potential for cementation with days strorage in chute

In principle, the 18 inch diameter is more than sufficient I suggest, if there is a possiblility of material storage in chute, then make the chute to have a flanged removal section to rod out in case the material becomes agglomerated.

The flow velocity will likely be very high on arrival. Dust will occur on impact at receiving station.

Therefore, you must be cognizant of the kinetic energy on arrival at chute discharge and its impact to your conceived design. ■

Another point:

THe full chute internal length should be accessable to replace worn liner material. Thus the design of chute should accomodate this criteria. ■

Dear Mr. Farooq,

what type of plastic pipe you are using as liner.I donot think ordinary plastic pipe will last long as wear liner. Liner should be wear resistant.

I donot think with Mild steel pipe material iron contamination.will be there. Instead of 3 mm MS pipe plus plastic pipe liner you can go straight to 6 mm thick Ms pipe without liner as liner replacement will be difficult you can straight way change worn out flanged pipe pieces.

A R SINGH ■

Dear Farooq,

I would not recommend a mild steel to survive the proposed 80 ft chute drop at 3 or 6 mm thick wall, given your comments on rock strength and potential abrasive index. The liner material must be sufficient. This can be catagorized by experience or abrasion testing. Plastics such as TIVAR-88 may be adequate. Realize the flow regime will likely be sliding more than rolling. unless the product is somewhat rounded.

I would tend to believe, a 6mm plastic liner would be sufficient. and only half the pipe needs the liner (180 trough) ■

Dear Farooq,

It is always desirable to provide wear resistance liner. In case you get wear resistance plastic liner in pipe shape it is better to provide. in any case pl do not provide ordinary Plastic pipe as liner

A R Singh ■

I would recommend that you go with a schedule 10 - 316 stainless steel pipe.

18" is rather large for 20 TPH. I had 17 years of working with those flow rates in fine and coarse salt and I would recommend 8" diameter would be more than adequate at 70 degrees.

Now I work in flow rates where we are running 2000 TPH in a 20" pipe.

The stainless steel will shine up very smooth and never cause qany comtamination problems.

Gary Blenkhorn ■

Gary,

I agree with the smaller diameter to maybe 10 inch. Certainly, stainless will flow and improve with time.

The thread starter asked not to use steel. Do you know that the iron in the stainless will not contaminate the product? ■

Larry

You are correct that iron is a contaminant that is why I suggested 316 SS actually 316 Type L would even be a better choice. The chemical composition of 316 contains a max .08% carbon while 316L contains only .03% carbon. The inside surface of the 316 stainless steel will shine up right away and create a barrier against corrosion.

If abrasion is a concern and the high content of nickle and chromium in the stainless steel will create a contaminant to the process then it mat be a concern. Can the thread starter please provide more details on the process and other possible contaminants?

With respect to CaCO3, MgCO3.

from http://ceramic-materials.com/cermat/material/273.html

"iron contamination can contribute to a cream color in the fired glaze. "

From http://www.mcnallyinstitute.com/04-html/4-1.html

"The basic resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a "passive" film which is resistant to further "oxidation" or rusting. The formation of this film is instantaneous in an oxidizing atmosphere such as air, water, or many other fluids that contain oxygen. Once the layer has formed we say that the metal has become "passivated" and the oxidation or "rusting" rate will slow down to less than 0.002" per year (0,05 mm. per year)."

Gary Blenkhorn ■

Dear farooq

I dont feel ordinary plasic pipe will last more and will contaiminate

the dolomite. you can go with rectangular chute having HDPE Liner . chute size can be 200 mmx200 mm 6 mm thick with liner

A R SINGH ■