Minimum Feasible Capacity of Specialty Grades of Alumina Refinery

Hi Friends,

In earlier post, we have already discussed about minimum feasible capacity of smelter grade Alumina refinery which is techno-economically viable to set up in any part of the globe. In present post, we will briefly discuss about minimum feasible capacity of specialty grades of  Alumina Plant.

It is well known fact that specialty grades of hydrate and alumina are marketed at premium price ranging from three times to five times of those of chemical grade hydrate and standard calcined alumina where as the production of specialty grades of hydrate and special alumina are approximately 15% to 20% higher than those of chemical grade hydrate and smelter grade alumina respectively. Because of increasing demand of specialty grades of hydrate and calcined alumina for various non-metallurgical applications all over the World has tremendous market potential with reasonably high profit margin. Thus, it gives us opportunity to think about the minimum feasible capacity of specialty grade alumina plant which can give high returns resulting in low pack back period. 

The preliminary study reveals that specialty grade alumina plant with 25,000 tonnes per annum production capacity is the minimum feasible capacity considering the availability of basic technological equipment for continuous operation on commercial scale. The estimated capital investment for such plant will be around US$ 25 million excluding the investment towards land and infrastructure facilities. The average manufacture cost of specialty grade alumina is estimated at around US$ 310 per tonne inclusive of all financial charges where as minimum  selling price will be ranging from US$ 600 to US$ 1000 per tonne of specialty grade alumina. Taking average level of sales realization at around US$ 800 per tonne of specialty grade alumina, the pay back period for total capital investment works out to less than 3 years. Specialty grades of hydrate have more profit margin compared to specialty grades of calcined alumina.

The preliminary financial indices prompt us to go ahead for execution immediately. However, It is always advisable to check the following basic information before taking final decision for execution-

1. Availability of about 3.0 million tonnes of chemical grade bauxite,
2. Required utilities and services,
3. About 20 hectares of land for plant,
4. About 50 cubic meters per hour of industrial grade water,
5. Other basic input raw materials and skilled workforce.

In addition to all stated above requirements, the detailed feasibility study is a must to confirm the market scenario, fixing of product-mix, finalizing the required process technology and re-look at outcome of final financial parameters. Execution of such plants definitely require technical competence in process expert as a process technology supplier for the project, otherwise execution with superficial knowledge about the process may be detrimental for the stake holders in the project - this is just a word of caution from our expert team.

We feel that you will like the article on "Marketing potential of Special Hydrates and Aluminas".

These are just the basis to initiate working on this lucrative project. Please put your views / suggestions / remarks / comments, if any.

If you like this article, then please press your rating as  +1  .
Thanks and regards.

Rajendra Kunwar
rajendra@ceti.co.in
www.ceti.co.in

Design and Motor Rating Calculations for Bauxite Grinding Mills

Hi Friends,

In continuation to our earlier post on Efficient grinding system for Bauxite in Alumina refinery, we will discuss the methodology along with design calculations for sizing of Ball mill including the estimated motor rating with reference to a known mill operative in identical process conditions.The cross section of a typical Ball mill has been shown below just to have the physical feel of the main components of Ball mill and movement of grinding media inside in running condition. I am thankful to my friend who has developed this animation for schematic cross section of the ball mill in operation-

Schematic Cross section of Ball mill in Operation

It is evident from the above schematic diagram that size reduction of bauxite takes place due to impact action of balls and rubbing action of particles as well. The actual operating rotational speed of ball mill is controlled at around 60 to 80% of the critical speed of the mill derived on the basis of effective diameter of the mill as elaborated below. We have already discussed about the material of construction for ball mill liner and balls used as grinding media. We are presenting here the systematic approach to work out the dimensions (Diameter and Length) and motor rating of ball mill for successful operation for a typical capacity Alumina refinery as given below-

We have put all out efforts to present the calculations in simplified manner for easy understanding by one and all related to the subject. Hope, you will appreciate our attempts in preparing the concise and systematic derivations for such a complicated topic. Please put your views / remarks / suggestions / comments, if any, for further improvement.
Regards.

Rajendra Kunwar
rajendra@ceti.co.in
www.ceti.co.in

Bauxite : A Major Concern for Chinese Alumina Refineries

Hi Friends,

All of us are well aware that China has added the Alumina refinery capacities at faster pace during last decade though they have the limitation of quality bauxite for processing at economic level. Chinese bauxite is poor in quality as it has diasporic alumina coupled with very high reactive silica.

It will be prudent to mention here that diasporic alumina extraction is highly energy intensive and high reactive silica in bauxite causes higher Caustic soda consumption for alumina production. Also, the mining cost of bauxite in China is comparatively higher compared to other countries. Thus, imported bauxite from neighboring countries is mixed with locally mined bauxite before processing in plants. Following details will make the elaboration easy for understanding. 

Current production cost of calcined alumina in China is ranging from US$320 to US$380 per tonne of calcined alumina. The broad break up of cost components are outlined below-

• Bauxite : US$90 to US$170 per tonne of alumina
• Caustic : US$50 to US$60 per tonne of alumina
• Energy  : US$140 to US$180 per tonne of alumina
• Others   : Us$50 to US$60 per tonne of alumina.

Among Chinese Alumina refineries, Guangxi Alumina Plant has the lowest production cost at around US$320 per tonne of calcined alumina. However, production cost at Shandong Alumina Plant in China works out to around US$380 per tonne of calcined alumina.

The data published data clearly reveal that Indonesia had been the largest exporter of bauxite to China. In the year 2012, Indonesia exported over 36 million tonnes of bauxite to China where as the balance bauxite of about 9 million tonnes was exported by Australia, India and other countries.

Now, Indonesian Government has increased the export tax from 20% in 2012 to 50% in 2013-14. Also, the government has announced complete ban on export of bauxite from 2014 onward as they have decided to preserve their natural resources for the existing and upcoming Alumina plants in their country. The article on "Promising Alumina refinery projects in Indonesia" may be of interest to you.

Looking at the above scenario, it has become a very serious issue for China to keep their plants operative in years to come. Presently, China is consuming its total domestic alumina in their own Aluminium smelters for production of aluminium metal. 

In present crisis of bauxite availability from Indonesia, China is exploring the possibility to import bauxite from Guinea. But higher transportation cost of bauxite from Guinea will make the production cost further higher for production of calcined alumina in China.

Further, to enhance your data base, you may be interested to read Benchmark figure of Energy Consumption in Alumina Refinery.

We have assimilated the above information based on the published literature available on public domain in the interest of our friends of bauxite-alumina-aluminium fraternity across the globe.

We solicit your comments / remarks, if any.

Rajendra Kunwar 
rajendra@ceti.co.in
www.ceti.co.in