Drop forming method and sulphur polymer concrete process

Details Drop forming method and sulphur polymer concrete process Drop forming method and sulphur polymer concrete process

1999-04-26

2001-05-08

Michl, Paul R. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C264S007000, C264S014000, C528S503000

Reexamination Certificate

active

06228905

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a drop forming method for transforming a molten material or melt into discrete solid particles. It also relates to a method of producing a sulphur polymer stabilizer in particulate form and a method of producing a sulphur concrete.
BACKGROUND OF THE INVENTION
A sulphur concrete is a concrete mix in which sulphur is used as a binder instead of water and portland cement. Typically, a sulphur concrete comprises a mixture of sulphur with a filler material and an aggregate material. However, in order to preserve the strength characteristics of the sulphur binder it is necessary to introduce a stabilizer to prevent the transformation of monoclinic sulphur to orthorhombic sulphur and other crystallization effects. One such stabilizer comprises an olefinic hydrocarbon polymer which reacts with the sulphur to form a sulphur containing polymer, as described in U.S. Pat. Nos. 4,058,500 and 4,293,463, the entire contents of which is incorporated herein by reference.
One method of introducing the stabilizer is by reacting an olefinic hydrocarbon with elemental sulphur to produce a sulphur polymer stabilizer which is then used for producing the sulphur concrete. The stabilizer may be used immediately or at a later time.
A conventional process for producing the sulphur polymer stabilizer involves reacting the hydrocarbon with the sulphur in molten form and then pouring the resultant molten sulphur stabilizer onto a surface, allowing it to cool and solidify. Thereafter, it is broken up into pieces with machinery, such as a bobcat. The process creates a health hazard due to the dust produced. In addition, the product is subject to contamination. Furthermore, the resultant particles are inconsistent in size. This can result in a sulphur concrete mix of inconsistent quality.
It is accordingly an object of the present invention to provide a method for the production of a sulphur polymer stabilizer of improved quality with particles having a more uniform size. It is also an object of the invention to provide an improved sulphur concrete.
SUMMARY OF THE INVENTION
According to the invention there is provided a method of transforming a molten material or melt into discrete solid particles, comprising the steps of forming the melt into prills by passing the melt through a perforated member, dropping the prills onto a bed of powder material to coat the prills with the material in the bed and permitting the prills to cool, thereby to solidify into discrete solid particles.
The melt may comprise at least two components which are subjected to a chemical reaction prior to forming the melt into prills. In one embodiment, the two components comprise elemental sulphur and an olefinic hydrocarbon, the chemical reaction being the polymerization of the olefinic hydrocarbon with the sulphur to form a sulphur polymer stabilizer which constitutes the melt.
The chemical reaction may be carried out at a temperature in the range of from about 115° C. to about 150° C., preferably 140° C., and the melt may be cooled to a temperature in the range of from about 115° C. to about 125° C., preferably 120° C., prior to forming the melt into prills.
The polymerization may be permitted to proceed until the melt has a viscosity of about 30 to about 40 cp, preferably 35 cp, prior to cooling the melt for forming into prills.
The elemental sulphur and olefinic hydrocarbon may be combined at a ratio of about four parts elemental sulphur to 1 part of olefinic hydrocarbon by weight for effecting the polymerization, but other proportions are possible.
Also according to the invention there is provided a method of producing a sulphur concrete comprising the step of mixing aggregate material and filler material with elemental sulphur and a sulphur polymer stabilizer in a heated mixing vessel, wherein said stabilizer is in particulate form and prepared prior to said mixing by a method comprising the steps of subjecting elemental sulphur and an olefinic hydrocarbon to a polymerization reaction at an elevated temperature to produce a sulphur polymer in molten form, forming the molten polymer or melt into prills by passing the melt through a perforated member, dropping the prills onto a bed of powder material which is at a lower temperature than the prills to coat the prills with the material in the bed and permitting the prills to cool, thereby to solidify into discrete solid particles.
The powder material may comprise a filler material suitable for use in a sulphur concrete, such as silica flour.
Further objects and advantages of the invention will become apparent from the description of preferred embodiments of the invention below.


REFERENCES:
patent: 3742100 (1973-06-01), Boyum
patent: 3933956 (1976-01-01), Mavrovic
patent: 4058500 (1977-11-01), Vroom
patent: 4217127 (1980-08-01), Kone
patent: 4231991 (1980-11-01), Muller
patent: 4293463 (1981-10-01), Vroom
patent: 4343622 (1982-08-01), Bruynseels
patent: 5004799 (1991-04-01), Kohls et al.

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