Improvements in and relating to the production of coke

DETAILED DESCRIPTION We claim: 1.
A process for the production of coke which process comprises digesting coal at an elevated temperature with a solvent which includes non-recirculated solvent, filtering undissolved material from the extract, concentrating the extract and thereafter coking the concentrated extract while recovering the solvent for recirculation, characterized in that prior to use in the digestion of the coal, said non-recirculated solvent is subjected to coking under conditions comparable with the conditions under which the coal solution is subjected to coking until the coking of all the cokable components in the solvent under those conditions is substantially complete.
2.
A process as claimed in claim 1 characterised in that the solvent is one or more of the crude tar fractions known as anthracene oil.
3.
A process as claimed in claim 3 characterised in that the anthracene oil contains quantities of phenanthrene.
4.
A process as claimed in claim 1 characterised in that the coal solvent includes polycyclic aromatic solvents obtained from petroleum catalytic and/or thermal cracking operations.
5.
A process as claimed in claim 1 characterised in that the solvent includes an alkylated phenanthrene oil.
6.
A process as claimed in claim 1 characterised in that the boiling range for the solvent is 150.
degree.
C.
to 400.
degree.
C.
7.
A process as claimed in claim 6 characterised in that the solvent has a middle 90% thereof boiling between 250.
degree.
C.
and 390.
degree.
C.
8.
A process as claimed in claim 1 characterized in that the prior coking of the solvent is carried out at a temperature within the range of 450.
degree.
C.
to 550.
degree.
C.
and at a pressure sufficient to prevent substantial boiling of the solvent.
9.
A process as claimed in claim 1 characterized in that the solvent is a distillate of an aromatic solvent feedstock which distils at a temperature of between 500.
degree.
C.
and 50.
degree.
C.
below the maximum temperature in the digestion stage and at a pressure of not less than 0