Print page

Experts

Solids Processing

Solids Processing by Tom Blackwood, director of technology, Healthsite Associates

Tom Blackwood is director of technology at Healthsite Associates, Ballwin, Mo. Previously, he worked for Monsanto and related companies, including over 20 years as an internal corporate consultant on solids processing. His expertise covers design and operation of units for crystallization, precipitation, evaporation, drying and solid-liquid separation. He has written more than 85 external publications as well as many internal design guides.

Will thermal dispersion units separate the 'stickies'?
I am working in a paper mill. My co-worker wants to know about thermal dispersion units and how he can use it there to separate stickies from wood.
Category: Solids Processing

How to Avoid a Break in the Main Shaft Screw
We have a twin screw conveyor for transferring Na₂SO₄ as per spec data below. To avoid a break in the main shaft screw, I would like to install a torque limiter for safety device. What is your opinion and is there a best way to do this? Is there any torque limiter product that accommodates our screw design?
See the data below:

Product to be handled: Sodium sulphate (salt)

Chemical formula: Na₂SO₄

Density at 20 degree C: 2700 kg/M³

Bulk density: 1500 kg/M³

Shape of particles: Rhombic

Sieve analysis:
- above 0.1 mm: 70% by weight
- 0.06 – 0.1 mm: 15% by weight
- below than 0.06 mm: 15% by weight

Average particle size: 0.18 mm

Specific particle surface area: 68 M2/kg

Total throughput: 6000 kg/hrs dry salt, 6250 kg/hrs wet salt

Temperature: 40 degree C

Residual moisture: 3% - 4% by weight

Material of construction:
- all wetted parts: SS 316L
- all non wetted parts: SS 316L

Speed of screw conveyor: Fixed 36 rpm

Electrical data: 380/680 V, 50 Hz, IEC standard, IP 53, non explosion proof, F insulation class

Spec for geared motor: SEW EURO drive R107DV132M4, 7.5 KW, 36 rpm
Category: Solids Processing

Can you recommend formulas for calculating power consumption?
Can you recommend a formula or a reference to calculate power consumption for a screw conveyor and a pulverizer?
Category: Solids Processing

Decreasing Filtration Time
Our plant is currently investigating methods to decrease filtration time for one of our products. The process involves a neutralization reaction in which Calcium Salt of Dodecylbebzene Sulfonic Acid is formed. Sulfuric acid also exists in the raw materials, which leads to a secondary reaction that yields calcium sulfate. It is the calcium sulfate that is removed during filtration. Currently, a filter press is employed for the removal of the CaSO4. We are hoping to employ some type of agglomeration technique to improve the filtration rate.
Category: Solids Processing

Decrease Moisture
I have a fluidized bed dryer with five chamber (5 different fan). At fourth chamber (200 C) moisture of the product at about %1 but at final (cooling) stage before packaging it gain moisture because of the entering fresh air at 50 C. How can I decrease the moisture of 3000 m3/h air entering final stage or any other suggestion.
Category: Solids Processing

Solid dosing
Please suggest a system that can dose a variety of solids (powdery, free-flowing types) into a batch reactor for a batch process to cater to the accurate weighing of a variety of solids into a resin reactor using automatic systems.
Category: Solids Processing

Rotary vacuum drier operation
I request your guidance in improving operation of a rotary vacuum drier. We have a horizontal RVD with a central shaft for heating with 3 kg steam pressure and a ribbon blender. Our input is spray dried material with a bound moisture of 10% to 12% and output as dried product has less than 0.5% moisture. We face agglomeration problems. Typically, what should the loading capacity for a rotary Vacuum drier (RVD) be? Should we have a high vacuum to begin with? Also, should we stop heating once material has dried?
Category: Solids Processing

Inlet air fan speed
Which one is better — an inlet air fan working with a frequency converter or without? I want to achieve the desired speed to bubble the solid crystal easily during drying. Do you think that to control air exhausting from a fan with a butterfly vane is enough?
Category: Solids Processing

Particle void fraction
If I use the same material to fill a box with only large or only small particles, which box will weigh more?
Category: Solids Processing

Pellet flow in hoppers
How do you measure the flow ability of pellets in a hopper? Please show any details or illustrations.
Category: Solids Processing

Ideal slurry valves
In flowing slurries through 1-in., 1.5-in. and 2-in. lines and with pressures in the 150# ANSI range, are ball valves or plug valves better suited for this application and why? Assume 30 psid pressure drops across the valves.
Category: Solids Processing

Eliminate high fluoride
How do you eliminate high fluoride from a zinc-bearing oxidic material? Are there any chemical methods available?
Category: Solids Processing

Remove entrapped air prior to packing
How can entrapped air be removed before packing material, such as sand particles, conveyed pneumatically?
Category: Solids Processing

Pneumatic system for transferring fine sand particles
Can you send me details about a pneumatic system for transferring grinded fine sand particles?
Category: Solids Processing

Agglomeration methods for copper-containing ore
Known binding agents such as water glass are not stable in the low pH environment typically used in heap leach operations. Do you know of any effective agglomeration methods for fines generated during crushing of copper-containing ore prior to heap leaching of the agglomerated material?
Category: Solids Processing

Removing MIBK from a filter cake
We are having difficulty in removing MIBK from a filter cake prior to drying using methanol. It is necessary to reduce the MIBK content of the filter cake to less than 3% prior to drying to avoid clumping. However it takes 9-10 washings to reduce the MIBK to the desired levels. We have tried combinations of slurrying and displacement without much success in lowering the amount of washings. Is there a better way?
Category: Solids Processing