Production of eco friendly bricks from mine tailings in western australia Essay Example

Abstract

There exist extensive mining activities in Western Australia, which are also outlined in world’s list of mining jurisdiction. Various types of mining in Western Australia cover a wide range of minerals such as gold ores and iron ores. There are a lot of wastes generated in the refining processes of these ores. Such wastes include, mine tailings, waste water and other waste. For effective disposal of these wastes, the industries should reuse these wastes. Bricks should be made in a price efficient and ecologically pleasant way using mine tailings from various iron ore mine in the Western Australian region. This study presents a review of geopolymerization technology that can be used in making bricks from mine tailings in Western Australia.

Detailed Description

In the recent years, most researchers have opted for geopolymerization methodology in the production of mine wastes bricks. The methodology of Geopolymerization is a response undertaken by the aluminosilicates in extremely concentrated silicate or alkali hydroxide solution forming geopolymer which is a very firm material possessing amorphous polymeric composition containing various consistent Si-O-Si bonds. Dimas et al (p20) and Duxson et al (p10), highlight that the procedure encompasses dissolution of various compact aluminosilicate materials in robust alkaline solutions leading to the formation of silicalumina and polycondensation of various oligomeric species to create in organic polymeric materials. The process also leads to the bonding of various undisclosed solid particles in the last geopolymeric composition.

Performances produced by the geopolymer can not only be comparable to OPC, but it also displays various benefits such as high acid resistance, quick development of the mechanical strength, brilliant observance to aggregates, low or no alkali-silica reaction related expansion, considerably reduction in the production of the greenhouse gases and immobilization of hazardous and toxic materials (Ding and Zhang, p 60). Freidin (p15) tried out geopolymerization of group F and bottom ash to manufacture bricks without cement. Freidin employed glass water that had silica module of about 2.3 as alkali activator and the application of a various types of forming pressures in preparing different specimen tests. The end outcomes illustrated that, the bricks without cement produced by the use of geopolymerazation could easily meet various requirements of Israel Standard for the construction of concrete blocks.

Grutzeck and Diop (p14) researched the feasibility of using the aluminosislicate to produce bricks by the use of geopolymerization methodology. They utilized sodium hydroxide solution to serve as alkali catalyst and made the various tests specimen through compression of the sodium hydroxide concoction in the container with about 10MPa pressure. Grutzeck and Diop then considered the impact of the sodium hydroxide solution and the curing temperatures. The end results illustrated that the strength of the bricks increases with the curing temperatures and sodium hydroxide concentration.

C for two hours and grounded them inside the alumina globe mill; they then sieved the solution to < 120 μιη prior to using it. They used sodium hydroxide solution and sodium hydroxide plus the silicate mixture as the alkali catalyst. They also molded test specimens by use of a form pressure of about 15MPa in the fortify mold. Later, the molded specimens were left to establish under a room temperature for twenty four hours and later cure at various temperatures for various times before they were tested. o Mostafa and Mohsen (p160), conducted their studies on the deployment of the small kaolinitic clays in the production of polymer bricks. They activated the grey raw materials at a temperature of 700

The final results illustrated that the curing temperature and the type of alkali activator are greatly involved in influencing the behaviour of the geopolymer bricks. When the accurate alkali catalyst and proper and adequate curing temperature, then all the deliberated low kaolinitic clays are efficient in the production of geopolymer bricks. With the idea that huge quantities of copper tailings are often produced every year, and that the mine tailings are very wealthy in alumina and silica and can as well be adopted in manufacture of geopolymers, this discovery describes the possibility of using copper mine tailings in the manufucture of eco-friendly bricks in Western Australia (Mostafa and Mohsen, p 160).

Mine tailings can be used in the production of eco-friendly bricks by use of geopolymerization. The procedure for the production of bricks encompasses mixing the mine tailings with alkaline solution. The brick is then formed by compressing the mixture of alkaline solution and mine tailings under a specified pressure and obtaining the brick at a slight elevated temperature. Apparently, copper mine tailings has been found to be the most appropriate in the process described herein. Unlike other conventional methods of manufacturing bricks, the first-hand methodology does not use shale and clay nor demands high temperature kiln firing, hence, creating substantial ecological and environmental benefits. However, the procedure defined herein can be applicable to other types of mine tailings if they contain an appropriate quantity of alumina and silica that can allow geopolynerization to take place (Kuranchie, F et al).

Results and conclusion

Water absorption

It is important for the bricks to be able to absorb water more effectively. This quality illustrates the permeability of the bricks and shows the level of reaction for the fired bricks. Geopolymer bricks also possess good water absorption quality due to the high level of geopolymerization results in a permeable and less porous matrix. According to Freidin (p15), fly ash-based bricks with no hydrophobic addictives, their water absorption level reached its final worth of close to twenty five percent in one day. Frieman also illustrated that the ultimate water absorption was reduced by the addition of hydrophobic agent to below 10% after four weeks.

Bulk unit weight

There is a variation in the bulk of unit weight with various forming processes for the brick specimens prepared at 15M sodium hydroxide concentration and the original contents of water and cured at ninety degrees Celsius for seven days. Just as expected, bulk unit weight rises accompanied by the forming pressure and the original water content. The rise in the unit weight with the primary water content is as a result of huge amount of sodium hydroxide. Forming pressure increases with the unit weight up to a certain limit and then it drops. This is due to the loss of water hence making sodium hydroxide to be above the level of forming pressure.

Summery and conclusion

The likelihood of using copper tailings in the production of geopolymer bricks was done by undertaking various loose compression tests, SEM imaging, water absorption test and XRD analysis. These studies attempted to investigate the impacts of four various factors, that is, initial water content, sodium hydroxide concentration, the curing temperature and the forming pressure on the mechanical and physical properties, microstructure, and the composition of the formed brick specimen. According to the results, several deductions were made.

C.o Firstly, the geopolymer brick produced at 15M sodium hydroxide concentration possesses high UCS than the ones produced at 10M. This is true since higher sodium hydroxide concentration offers large amount of sodium hydroxide at given original water content needed for geopolymerization. Consequently, high original water content depicts large number of sodium hydroxide concentration hence increasing the strength of the brick specimen. Again, higher level of the forming pressure results to high level of compaction and hence higher UCS if there is no water squeezed during the molding process. In case the forming process is too high than expected, then sodium hydroxide and some water are lost thus decreasing the UCS. Finally, curing temperatures is a vital factor that influences geopolymerization and hence the strength the formed brick. There is continuous increase in UCS with the increase in the curing temperatures up to a given level when it declines with the curing temperatures. The optimal curing temperature for copper tailings studied is close to 90

Works cited

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Mostafa NY and Mohsen Q. Investigating possibility of utilizing low kaolinitic clays in the production of geopolymer bricks. Ceramics — Silikaty 2010;54(2): 160-168. Available at.
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