THE  MAIN  PRINCIPLES  AND  DEVICE  FOR

CONTINUOUS  BASALT  FIBERS  PRODUCTION.

Dr. Michael Ziv, “BASALT-TECH”.

michel998@013.net

1.      ABSTRACTS.

Uni components - The manufacturing of the fibers materials, based on mineral, vitreous, kaolin and other fibers is widely known and intensively developed in the world. However, in order expend to other/more advanced applications we need to improve the recopies and processes, and because it much more expensive , it hinders growth of production.

Multi components – Multi component composite materials for fiber manufacture calls for complicated technique for selecting and proportioning of more materials and feeding them to the production plant process.

Our product - continuous basalt fibers is a uni component natural raw material ( basalt rock stone). The production of continues basalt fibers is a base for further processing of many finished products. Almost all countries have natural purveyance of this raw material. World industry interest in these products is increasing rapidly in the last several years.

2. TECHNICAL ADVANTAGES. 

The continuous basalt fibers derived from basalt rock have proven technical characteristics and performance specifications. These fibers are cost-effective in comparison with the commonly used glass fibers and others (ceramic, carbon, Kevlar, etc.).

The main technical advantages are:

·        High chemical resistance, (especially to concentrated acids based materials).

·        High thermal resistance (thermo stability) and low flammability.

·        Low strength degradation at temperatures as low as – 200…250 deg. C and as  high as        +700…900 deg. C., and of high humidity.

·        High thermal and acoustic insulation properties.

·        Excellent adhesion to polymer resins and rubbers.

·        Relatively high mechanical strength, abrasion resistance and elasticity.

·        High dielectric properties.

·        Low water absorption.

·        Ecologically clean and non-toxic.

 The following table shows some main compared features:

These technical futures and apparent superior cost-effective position make basalt fiber suitable material to fill in the gap between fiber glass and more resistant but much more expensive fibers, like ceramic, carbon, etc.

3.        INTRODUCTION.

The technology process of basalt fiber manufacturing is based on the following major steps:

·        basalt rock pre-treatment.

·        melt furnace processing for continuous fibers.

·        processing for continuous threads.

·        downstream processing for fabric (cloth) and other applications to specific end-uses. 

The author of this paper has technical knowledge and practical combined experience of over 40 years in management of R&D projects in the fields of industrial and construction materials (e.g. concrete, basalt fibers, wood, etc.) . His group has experience in engineering design and production management of several manufacturing plants in the field of basalt fibers production and its applications. Most of the professional experience has been in Ukrainian and other former USSR industrial enterprises.     

From our experience, the main basalt melts parameters for achieving the needed properties of viscosity and crystallization (in fiber-forming zone of melt furnace),

determines the stability of the fiber forming process. The big iron oxide content of basalt stone, which makes a melt dark color, increase the homogenization period, crystallization temperature and make viscosity curve much more abrupt in comparison with aggregated glass compositions. These facts call for unique design of melting furnace that provides needed conditions for keeping melt homogenization  state under different phases of processing.

The typical plant for continuous mineral fibers production uses the vertical melt method for the production of the base fiber. The further textile processing of the base fiber (extraction, vertical dragging, initial processing and coiling), using other technology equipment oriented for filament and fabric manufacture.

The main disadvantage of these plants is non stability of the production process because of following reasons:

·   The melting volume is usually separated from fiber production part of plant and is connected to it trough the outlet of the melting process which is usually closed, opening only for discharge of melt to spinneret vessel with fiber-forming plate. Under this condition lot of foam is formed while melt discharging to spinneret vessel.

·   Besides, a new raw material portions usually fed to melting volume through one or two top openings. If we do not consider the existing melt level and the uniformity of rock feeding in fiber forming zone, it will disturb the  uniform distribution .

·   Today's feeding method to existing melt does not consider the melt level in fiber forming zone.

·   Between the fiber forming stage and the coiling apparatus there is usually  a device for structure fixing and separation processes which are not enough for product stability.

·   In the case of such raw material (as pure mono component natural basalt igneous rock) for continuous fiber production, the stability of production process is affected by additional problem. To the above mentioned reasons (homogenization, crystallization and viscosity), in a typical plants production, we have to consider the opacity of dark melt.

    This fact causes high heat absorption and hastened cooling down of its top layer. Heat transfer from walls of spinneret vessel to fiber forming plate is considerably decreases. In case of pure basalt raw material, a drastic local melt cooling (in the loading zone), escorted by bubbling of the melt. This cooling causes a rapid abrupt in melt transportation to production part and stipulate melt foaming even with a little temperature difference,. The melt foaming disturbs the homogeneity of melt’s structure. The none homogeneity effects melt dosage above the fiber forming plate because of the unstable hydrostatic pressure, temperature and viscosity of the melt in the fiber forming zone.

     All this reduces to non-uniformity of the melt mass, instability of all fiber process determined the fiber quality and it's further correction (hardening).  

·   To increase the quality of the fibers it is widely adopted the blending (aggregation) operation. Natural compositions of basalt blended with additional aggregates in proper portions to achieve known compositions.

    This permit's keeping the needed study-state conditions on known equipment. The disadvantage of this method is factually using of multi component raw material and, as a consequence, manufacturing complication .

We invented and patented in Israel the plant for fabrication and hardening of quality continuous fibers from pure mono component natural basalt igneous rock without any additional blending (aggregating). 

4.      DESCRIPTION.

The raw material comes into the plant aggregated in special rigid limited size, it is pre heated in the oblong loading without contact to existing melt. This loading is all along the melting basin's length and connects to the melting area via inclined to the horizontal plane.

At the end of the inclined plane is placed a spherical melting bath which is open to the spherical production part .After reaching the wanted quality the melt is flowing from the bath to the production part and then goes through the spherical gauze filter with wanted temperature and viscosity .The melt is now in the fiber forming zone with spinneret plate on its bottom (see involved drawing). All melting basin is closed hermetically to atmosphere. The melting bath and the spherical production vessel has a special computed relation between depth and sphere diameter of both of them.  

In order to reach uniform melt outflow without pulsation or orifice capping

We have to maintain the followings:

-         To keep the determined residual of temperatures in both volumes.

-         The definite melt level upon the fiber forming plate for keeping definite hydrostatic                       pressure.

-         Receiving of needed melt mass viscosity and temperature.  

5. MAIN ADVANTAGES.

As it was found by experiments with different sorts of pure natural basalt igneous rock, such main principles of melt basin design makes a good chance for quality continuous fiber manufacturing with minimum micro-cracks on fiber surface.

Besides, it make possible to use the main device of such designed plant for vertical melt method of basalt continuous fiber of  7 micron diameter with small design changes of fiber forming plate. Production of basalt continuous fiber of 7 micron diameter contributes further widening applications in lots of additional fields.

Please do not hesitate to approach us for any further information, which will be provided promptly and gladly.  michel998@013.net

 References :

1)      M. Thring “ The science of flames and furnaces”. Chapman & Hall LTD. 1952

2)      V. Fridman and V. Grigerih “Insulation of glassmaking furnace”.

          “Fachausschussberict der Dgg”, #33,1935.

3)      Gill G.S. “Comments about some American high-temperature furnaces”.

           “ J.Soc. Glass Techn.”, 31,1947, 94.

4)      Rybo G. “Heat transfer in glassmaking furnace”.“Verr. Et Refr.”, April,4.1947,

5)      “Fiberglass”, edited by M.S. Aslanova,1980, 33.

6)      M. Makhova, G. Gorbachev and oth. “Production of super thin fibers from igneous

         rock melts”. “Glass and ceramics” 8, 1984, 18

7)      Tutakov O.V., Tutakov A. O., Bozhko V. I. and oth. “Reprocessing of basaltic

          continuous filament covered with polyvinyl acetate emulsion”. “Chemical Fibers”

          VNII PV, Mytishchi, Russia, Nov.-Dec. 1992.

8)      US Patent 2,978,744.

9)      US Patent 4,149,866.

10)    US Patent 5,352,260.