Specifications and Applications of Dry Coarse Hydrate

Hi Friends,

In continuation to our earlier discussions on specialty grades of hydrate, we will discuss here the specifications, broad process route and applications of dry coarse hydrate. Dry coarse hydrate is the special hydrated alumina  having wide range of applications in industries.

Product Specifications:

Typical quality specifications of Dry coarse hydrate are tabulated below-

Al₂O₃: 64.0% min.

Fe₂O₃: 0.012% max.

SiO₂: 0.012% max.

Na₂O: 0.25% max.

Moisture: 0.50% max.

LOI at 1100^oC: 34.0% min.

Minus 45 microns: 6-8%

Production Process:

Chemical grade hydrate produced in Bayer’s circuit is used as feed stock for production of dry coarse hydrate. The process for production of dry hydrate suitable for various non-metallurgical applications envisages the removal of physical / superficial moisture from feed Bayer hydrate. However, the chemically bound water of crystallization and structure of hydrated alumina molecules will remain unaffected.

Hydrate being granular, powdery and porous material; Steam Tube Rotary Dryer is the most appropriate choice to be used as main drying equipment because of under mentioned key advantages over others:

§           No fear of contamination of the product.

§           No material losses.

§           No environmental problem.

§           Ease of operation.

§           Low capital investment and

§           Lower operating cost.

Steam tube rotary dryer is considered as the basic equipment taking into account the physical characteristics of Bayer hydrate as feed material and desired quality of dry hydrate as product. Chemical grade being mild sticky in nature, a combination of chute and screw feeder is the right choice for feeding moist hydrate to dryer.

In Steam tube dryer, method of constant temperature drying is adopted and saturated steam at suitable pressure used as heating media for removal of unbound moisture. Mode of heat transfer from steam to hydrate takes place through conduction only. The dried product hydrate is discharged to the product storage using belt conveyor. In storage shed, the product hydrate is stacked in packed form using High Density Poly Ethylene (HDPE) bags with poly- liner for dispatch. Storage of dry hydrate in loose form is avoided as it may absorb moisture from atmosphere because of its hygroscopic properties.

Industrial Applications:

Major applications of Dry coarse hydrate are listed below-

(i)   Manufacture of glass,

(ii)     Glazed ceramic tiles,

(iii)    Catalyst.

 I presume, you are satisfied with the elaborated facts and figures. I have broadly presented the data / informations of public domain nature because of my limitations. However, I will welcome your views / suggestions / remarks / comments for further improvements in future.

  Regards.

  Kunwar Rajendra