Plastic and nonmetallic article shaping or treating: processes – Formation of solid particulate material directly from molten... – Coated particles
Patent
1979-05-07
1982-11-16
Hall, James R.
Plastic and nonmetallic article shaping or treating: processes
Formation of solid particulate material directly from molten...
Coated particles
264 12, 264DIG51, B01J 216
Patent
active
043594344
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a process for granulating melts, particularly glass melts, ceramic melts, metal melts and melts of metal alloys, and may be applied with particular advantage to the granulation of blast furnace slag melts. The invention also relates to the production of an improved granulate.
In the case of metallurgical slags, the melt is frequently poured into a ladle which is carried to the slag dump where the slag is either removed from the ladle in the form of an already hard block or is cast in liquid form and left to harden on the dump. In many cases, slag melts are also converted into granulate by one of the known quick-cooling techniques, for example by pouring the slag into water. The first of these processes is uneconomical and results in atmospheric pollution. By contrast, the second process is more economical because the granulate may be used inter alia as an additive, for example as an aggregate for concrete.
However, all conventional processes for granulating melts, particularly slag melts, are attended by disadvantages and deficiences including inter alia loss of the heat content of the slag melt. In addition, the granulate can only be used to a more or less limited extent depending on the particular process adopted. Moreover slag and metal melts are extremely difficult to granulate in water on account of the danger of explosion. For this reason, steel slags for example are not granulated in water. By contrast, pig iron is granulated in water, although large quantities of water are required, in addition to which elaborate safety measures have to be taken.
The object of the present invention is to provide a process for granulating slag melts, glass melts, ceramic melts, metal melts and melts of metal alloys, particularly blast furnace slag melts, which enable the melts to be granulated without having to be kept hot for prolonged periods, i.e. without any need for additional energy. Additional objects include provisions for the granulate to be divisible into fractions having different properties and for a controllable reaction and/or association between the melt and fine-grain particles.
According to the invention, this object is achieved in that the melt is shaped into a melt film moving freely in a predetermined direction and is caused to intersect at a predetermined incidence angle a with a faster moving stream of fine-grained, solid particles and/or gas (particularly inert gas), and is thus atomized into a fan-shaped distribution of droplets over at least part of the opposite angle b to the incidence angle a.
The process according to the invention affords the advantage that granulation can be carried out in the open without any danger of explosion and the further advantage that the fan-shaped distribution of the droplets (which cool into fine-grained granulate) makes the hot granulate easier to collect in a fluidized bed.
According to the invention, the granulate may be divided into fractions on collection in dependence upon the distance between the point of collection and the point at which the flow of melt meets the stream. In this way, the granulate may be divided up into fractions differing in their properties, particularly their grain size, density and/or material composition. This is of particular advantage in cases where it is intended to granulate metal melts or melts having a considerable metal content and to separate completely metallic or predominantly metallic granulate particles from partly metallic or non-metallic granulate particles.
The process according to the invention affords the further advantage that the solid fine-grained particles, by digestion and/or inclusion in the still liquid melt, are firmly united with the melt in the granulate, so that a permanent unbreakable connection is established between the melt and the solid particles. The process according to the invention affords the further advantage that predetermined reactions can take place between the melt and the solid particles.
The incidence angle a between the flow of melt and the stream is prefera
REFERENCES:
patent: 3532775 (1970-10-01), Brondyke et al.
patent: 3533776 (1970-10-01), Coates
patent: 3655837 (1972-04-01), Reed et al.
patent: 4011290 (1977-03-01), Blomqvist et al.
patent: 4238427 (1980-12-01), Chisholm
Hall James R.
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