GB782345A - Improvements in or relating to processes for preparing coking blends from different coals - Google Patents

Abstract

782,345. Materials for making coke. BURSTLEIN, E. M., and SOC. DES ACIERIES DE LONGWY. Jan. 14, 1954 [Jan. 19, 1953], No. 1141/54. Class 55 (2). In a method of producing high-grade coke from crushed or fine coals of different types the coals are formed into at least two separate mixes A and B, the mix A containing the fusible coal or coals, and the mix B containing the inert coals and any foreign additions such as coke dust, semi-coke and pitch, and the mix B is given a grain size m between 0.5 mm. and 2.0 mm. by grinding in a progressive and controlled manner the only particles of the mix having a grain size > m while mix A is sieved on a screen having a mesh size M > m and the oversize is progressively ground to give the mix A a grain size lower than M, a second granulometric cut of the thus treated mix A is made on a sieve having a mesh size m<SP>1</SP> # m and the oversize is progressively ground to a grain size < m and the remainder of the mix A is mixed in desired proportions with the ground mix B and the portion of the mix A ground below a grain size m, the resulting mixture is coked at a high, moderate or low temperature. In order to classify coals into one of the mixes A and B use is made of their fluidity characteristics in the temperature range 300-500‹ C. determined e.g. by means of Gieseler's plastometer. In the arrangement shown in Fig. 1 coals of mix A pass through a mixer T1 and are screened on a screen a having a mesh size 2-6 mm., e.g. 4 mm., the oversize passing through a variablespeed grinder D and passing again through mixer T1 to be rescreened on screen a. The screenings from screen a are screened on a screen b having a mesh size 1-4 mm., e.g. 2 mm., the screenings from screen b pass to a final mixer H while the oversize is fed to a grinder G and circulated in a circuit together with coals of mix B. Coals of mix B are fed together with the oversize from screen b through a mixer T2 and screened on a screen c having a mesh size 0.5- 2 mm., e.g. 1.2 mm., the oversize is recirculated through the grinder G, mixer T2 and rescreened on screen c while the screenings are blended with the screenings from the screen b in the mixer H and the mixture is coked. In a modification the screen b and the mixer H are omitted and the screenings from the screen a are circulated in a circuit with the coals of mix B. In the arrangement of Fig. 3 the screen e on which mix A is screened has a mesh size between 2-6 mm., e.g. 3 mm., and the grinding circuit for coals of the mix B includes an additional screen f having a mesh size between 2-6 mm. The oversize from screens e and f pass through the grinder D and are rescreened on screen f. The oversize on screen g is ground in the grinder G and recirculated. In a simplified form of this arrangement grinders D and G are combined. A purifier such as a pneumatic separating table may be incorporated in the various circuits described to reduce the ash and sulphur content of the coke produced. Oil may be sprayed on to the coals in the mixers T1 and T2. Specifications 680,451 and 782,346 are referred to.