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Production of better quality perlite fillers

#A-1167


The New Technology for Production of Better Quality Perlite Fillers and Materials on Its Basis

Tech Area / Field

  • MAT-OTH/Other/Materials

Status
8 Project completed

Registration date
20.07.2004

Completion date
18.12.2008

Senior Project Manager
Tyurin I A

Leading Institute
NPF "Stone & Silicates", Armenia, Yerevan

Collaborators

  • National Technical University of Athens / Department of Mining Engineering and Metallurgy, Greece, Athens\nNational Technical University of Athens / Laboratory of Heterogeneous Mixtures and Combustion Systems, Greece, Athens\nNational and Kapodistrian University of Athens / Department of Geology, Greece, Athens\nInstitute of Geology and Mineral Exploration / LITHOS Quality Control Laboratory of Ornamental Stones, Greece, Peania\nNational Research Council / Institute of Science and Technology for Ceramics, Italy, Faenza\nInternational Bureau for Environmental Studies, Belgium, Brussels\nUniversity of Potsdam / Institute fur Geowissenschaften, Germany, Potsdam

Project summary

In this project it is planned to develop and research a technology for production of better quality perlite filler with stable and predictable set of characteristics. This technology is an innovation in perlite production practice, as it allows to classify the starting material, i.e. the perlite rock, by its density in order to optimize the parameters for material refinement and perlite expansion.
Analysis of scientific- technical literature on production of lightweight porous filler from perlite crude, shows that there are significant achievements in this area - such as designing perlite expansion furnaces and their development, determination and control of physico-mechanical and physico-chemical parameters of the rock, as well as regimes of preheating and expansion.
However this is not enough for provision of effective production of expanded perlite and materials on its basis as the used filler has no guaranteed and optimal set of characteristics, as it directly depends on the homogeneity of the perlite rock.
The complex structure of perlite deposits as well as non-rational technologies used for their mining, which does not take into consideration the geological particularities of dimensional allocation of perlite rock and their different species, causes a low quality and efficiency in the extraction of perlite rock. A characteristics feature that is often observed, is that the perlite flow can be considered as a zonal body, along the bedding of which different types of perlite (of different densities), as well as obsidians are met.
The only method of perlite mining used in the worldwide practice has serious disadvantages – it doesn’t ensure the homogeneity of the raw material. The range of changes of physical and technical characteristics of perlite is wide, particularly the density, which is changing along the bedding of the volcanic flow, as well as with its spatial distribution. The density ranges from 900 to 2200 kg/m3.
As a result of bore-explosive works and excavations in perlite deposits with complicated structure, we get raw material with mixed perlite species, which have different densities. The narrow grading of primary and secondary crushed raw material, which is provided in normative documents, doesn’t solve the problem of ensuring the homogeneity of the perlite for expansion, instead the heterogeneity even increases during this process.
Getting homogeneous raw material from perlite deposits is a difficult problem, but it is quite possible to solve it. With a scientific approach it is possible to design brand new ways of perlite rock preparation with stable and improved technical and technological characteristics. We intend to use non-traditional methods of perlite mining by selective-thin grooving of layers in order to prevent the mixing of perlites with different density.
Preliminary investigations that we have made (Aragats perlite), show that there is a dependence between physico-technical and technological characteristics of the rock and its density. As a consequence of this, density is chosen as a main criterion for evaluating the quality of the raw material.
The core of the method is the following classification of perlite from a given perlite deposit by its density:
700-1000 kg/m3 – pumice-type
1000-1300 kg/m3 – porous
1300-1600 kg/m3 – slightly porous
1600-1900 kg/m3 – dense
1900kg/m3 and more- massive.
Each density class has its optimal regimes of elaboration and rational ways of usage.
So it is necessary to make selective mining and separate crushing of different types of perlite. This will enhance the efficiency during the expansion process and will allow a considerable decrease in energy expenses. The existing crushers are designed for crushing of durable rocks and have a low elective capacity leading to a significant amount of over granulated material.
The usage of a jaw crusher (brand SM-741) will allow to reduce energy expenditure for crushing porous species by 55%, and for slightly porous species by 15%. So it is recommended to use either low-powered crushers for porous and slightly porous species or use a spare regime for their crushing. If the density of the crushed raw material is constant, the crushed product will have stable characteristics, and its granule-metric composition will be dependent on product density.
Our investigations show the dependence of characteristics of the expanded perlite-such as density, water absorption, specific surface, thermal conductivity, from the size of particle and from the density of bed rock.
Using Aragats perlite deposit raw material, that is homogeneous in density and size, we can get 13.8 m3 expanded perlite from 1m3 raw materials, but using the traditional technology we can get only 9m3. So the new method is 35% higher in efficiency.
So, the proposed technology allows to produce higher quality filler with stable guaranteed characteristics and with improved economy in its production process.
We have also made a comparative analysis of the acoustic and insulation materials characteristics, using common expanded perlite, satisfying the requirements of GOST 25226-96, brand M75, and also using filler with a higher quality. The usage of higher quality filler will give the opportunity to reduce its usage by 10% without changing the physico-technical characteristics, thus to reduce the cost price, as the filler is the most expensive component. Usage of such filler material is also very advantageous in terms of ecology – the stone resources are not revived in the nature, and their rational and careful usage is very important. As ecological aspects of building materials is getting more important in all areas of human activities, we made preliminary measurements for the determination of radioactive parameters in various perlite species. We concluded that the radioactivity decreases with increasing density (from 1000 to 2000 kg/m3) and decreasing size fraction (from 5,0 to 0,14 mm).
Thus, we have all the bases to affirm, that the suggested method of getting higher quality porous aggregate with guaranteed set of characteristics is economically more effective than the widely used method.


The goals of the project are:

- Investigation and establishment of consistent patterns of changes of physico-technical and technological characteristics of perlite rock and interconnections between them, as well as the exposure of the most reasonable (basic) criterion of its complex evaluation.
- Development of methods for determination of basic quality evaluation criteria for the raw material in the quarries, which will enable the operative quality control for the mining and manufactured raw material.
- Evaluation of dimensional allocation of the perlite rock and its species in the perlite deposits according to their depth and expansion. This evaluation will allow to specify the main elaboration characteristics for getting quality raw material for expansion.
- Development of a rational technology and bases of the characteristics of the mining works especially for mining of raw material for expansion.
- Investigation of mechanism for changing the characteristics of the rock, which will influence the process of expanding during its crushing.
- Analysis the influence of characteristics set by certain criteria, on the characteristics of expanded perlite and its investigation by modern physico-technical and physico-chemical methods.
- Investigation of the possibilities of a controlled change of characteristics of perlite material, produced by using improved aggregate.
- Synthesis of new compounds, taking into consideration the structural differences and physico-technical characteristics of expanded perlite.


As a result of this project the following problems will be solved:

- Development of a new low-resource and low-energy consuming technology to produce aggregates with improved and predictable characteristics.
- Creation of a new complex evaluation method for perlite-fields and a rational technology for their elaboration.
- Development of recommendations for effective usage of perlite rock, expanded aggregate and corrections made in the normative-technical documentation concerning the classification of the rock by densities.
- Development of the new wood-substitutes composites, on the bases of improved aggregates and fiber components.
- Reorientation of highly qualified scientific staff for peaceful problems solution and for encouragement of investigations and engineering works for peaceful purposes.
- Integration of the scientists into the international society.
The staff of the CJSC Stone and Silicates” has worked on the investigation of perlite rock, development of effective technologies and production of expanded perlite and perlite materials for a long period.
The authors of the project invite scientific collectives, investigation organizations and companies dealing with extraction and production of expanded perlite, as well as inpidual experts and scientists from Europe, USA, Japan and Korea for cooperation.
We also suggest the organization of joint seminars and scientific researches.


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