US 2550838 A
Description (OCR text may contain errors)
Patented May 1, 1951 PROCESS FOR MAKING GRAN ULATED PITCH Andr Macq, Uccle, Brussels, Belgium, assignor to Union Chimique Belge, Societe Anonyme,
Brussels, Belgium N Drawing. Application May 6, 1946, Serial No.
In Belgium August 3, 1944 Section 1, Public Law 690, August s, 1946 Patent expires August 3, 1964 The pitch which forms 50% of coal tar is used to a large extent in the making of coal briquettes. Sometimes it is conveyed to the place of use in liquid form, just as it leaves the retorts, by
means of heat insulated and heated trucks, but
slightest rise in temperature the pitch sticks and the detached blocks reunite.
In order to obviate these drawbacks, granulation of pitch has already been suggested, but the known processes of running liquid pitch into a flowing stream of water yield mixtures of irregular fragments containing hollow granules,
- threads and scales, which render the mass asa whole non-homogeneous. Moreover some humidity still remains and the occluded water is a nuisance.
Processes are also known for the setting of pitch en masse in water in the form of rather wide sheets about one centimetre in thickness, with subsequent drying and breaking up.
The object of the present invention is to obtain pitch in the form of compact granules, approaching the spherical form, containing no occluded Water, and provided with a protective coating which prevents the granules from coalescing even after prolonged storage. The pitch in the form of granules which do not stick is easy to handle and can be treated by mechanical handling devices. In this form it is, moreover, particularly suitable for the various uses to which it can be put.
In the improved process according to the invention, the liquid pitch, heated to 150200 degrees centigrade, is granulated by letting it run out of a container, either fixed or having a rotary or other movement, with perforated walls or bottoms, into a liquid in movement containing substances which after drying leave on the surface of the granules a thin layer which prevents sticking. The addition of these substances to the liquid is the essential feature of the invention and will later be more fully described.
The dimensions of the granules depend on the diameter of the perforations in the container,
on the outflow head of the liquid pitch and on the speed of the liquid in movement, which permits of varying them as desired, while pre- 3 Claims. (01. 18-473) a manner known per se.
2 venting the formation of threads (filaments) or occlusions.
After cooling, the granules are separated from the liquid and dried. The drying may be done by anappropriate means, for instance, by means of a current of air'and with the aid of a source of outside heat. It is however an advantage to separate the granules as soon as their surface is sufiiciently hard to ensure their maintaining their shape. The drying of the granules is then done in the pipe or channel which delivers them into a storage silo, without the employment of external heat, under their own heat in If water alone were used as the liquid in which the granulation is completed, the granules would weld together again within a few days. This is avoided according to the invention by an addition to the water of inorganic or organic substances only slightly soluble or insoluble in pitch, soluble or insoluble in water, non-hygroscopic when dry, which leave on the dried granules a thin layer, thus preventing the subsequent sticking together of the granules into a single means.
As substances suitable for this purpose there may be mentioned'by way of example alkaline chlorides and sulphates, the sulphates, hydroxides and carbonates of the alkaline-earth metals and magnesium, finely divided mineral substances such as talcum, silica alumina, and also the dusts and schlamms of carbonated substances. Preferably those are selected which do not change the appearance of the granulated pitch at all or very little and which do not appreciably increase the content of non-calcinable residue. In addition the liquid can be made heavier by the dissolution or suspension of substances other than the above-named, with a view to facilitating the separation of the granulated pitch.
The substances added to the liquid may if so desired enter into chemical action with one or another of the components of the pitch and thus modify the properties which are exercised on the surface of the materials, such as the surface tension for example, contributing to reducing the tendency of the granulated pitch to set together in a mass.
By way of comparison granulation of pitch from the same manufacture was effected in pure water, in water saturated with Ca(OH)2 and in water containing an excess of Ca(OH)2. After drying the granules and stacking at heights of 4 to 5 metres for 166 hours, it was found that those obtained in pure water began to stick together 3 at the test temperatures of 30 degrees centigrade and that, at the test temperature of 35 degrees centigrade they had already become a single block. On the contrary, the granules formed in water saturated with Ca(OH)2 or in dilute milk of lime showed not the slightest tendency to stick together at the same test temperatures and even withstood a prolonged storage at a temperature of 38 degrees centigrade.
When it is anticipated that the granules of pitch may be exposed to higher temperatures, for example, during transport, it is advantageous to subject them to an additional dusting with one of the substances mentioned above, preferably in the loading hopper.
1. A process of making coal tar pitch in the form of compact granules free from occluded liquid and substantially non-sticky at normal handling and storage temperatures, which comprises melting the pitch, running the molten pitch in the form of thin streams into a moving body of water containing substances which are insoluble or only slightly soluble in pitch, non-hygroscopic in the dry state, and which form a thin protective anti-sticking layer on the surface of the granules after drying, separating the granules from the water and then drying them.
2. A process of making coal tar pitch in the form of compact granules free from occluded liquid and substantially non-sticky at normal handling and storage temperatures, which comprises melting the pitch, running the molten pitch in the form of thin streams into a moving body of liquid containing substances selected from the class consisting of alkaline chlorides and sulphates, sulphates, hydroxides and carbonates of the alkaline earth metals and magnesium, finely divided mineral substances such as talcum, silica alumina, dusts and schlamms of carbonated substances, which form a thin protective antisticking layer on the surface of the granules after drying, separating the granules from the liquid and then drying them.
3. A process of granulating and coating pitch which comprises heating pitch to 150 to 200 centigrade, allowing the molten pitch to run out of a perforated container into a moving body of water containing Ca(OH)2, separating the granules after solidification and cooling and drying them, whereby a thin, protective, anti-sticking layer is formed on the surface of each granule.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,008,469 Prince July 16, 1935 2,136,208 Fehr et a1. Nov. 8, 1938 2,311,389 Hawks et al Feb. 16, 1943 FOREIGN PATENTS Number Country Date 457,076 Belgium Nov. 13, 1945