http://rdf.ncbi.nlm.nih.gov/pubchem/patent/GB-859264-A
Outgoing Links
| Predicate | Object |
|---|---|
| assignee | http://rdf.ncbi.nlm.nih.gov/pubchem/patentassignee/MD5_51e551c7e0bcaebbb21cbb56ded7219d |
| classificationCPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentcpc/C01G37-14 |
| classificationIPCInventive | http://rdf.ncbi.nlm.nih.gov/pubchem/patentipc/C01G37-14 |
| filingDate | 1959-04-30-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationDate | 1961-01-18-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| publicationNumber | GB-859264-A |
| titleOfInvention | Improvements in or relating to alkali metal bichromate purification |
| abstract | <PICT:0859264/III/1> Sulphate impurities are removed from alkali metal bichromate solution by adding an alkaline earth metal dichromate solution to provide an alkaline earth metal/sulphate ratio of at least 1:1, and filtering off the precipitated alkaline earth metal sulphate thus formed. The alkali metal bichromate solution to be treated is first concentrated to about 60 DEG Baum<\>ae, to crystallize out at least a part of the sulphate impurities. Alternatively the alkaline earth metal dichromate may be formed in situ by adding chromic acid and an alkaline earth metal carbonate or oxide to the alkali metal bichromate solution. Thus a chrome ore, mixed with sodium carbonate and lime may be roasted in a rotary kiln at 2000 to 2200 DEG F., cooled and leached to form a raw liquor containing for example sodium chromate, vanadate and aluminate. The pH of the raw liquor is reduced to 8.5 to 9 by the addition of sulphuric acid thereby precipitating and removing alumina; the pH is then reduced to about 4.4 by sulphuric acid addition and a solution concentrated to about 60 DEG Be. and cooled to about 24 DEG C. whereupon the bulk of the sodium sulphate crystallizes out. The red liquor so obtained is treated as shown in Fig. 2 by the addition of an alkaline earth metal dichromate freshly prepared from chromic acid and the alkaline earth metal oxide. Such addition may be effected to the red liquor before or after concentration to about 70 DEG Be. The solution is thereafter cooled and the alkaline earth metal sulphate crystallized out after standing to allow the crystals of at least 5 micron size to grow. The finished alkali metal bichromate is then recovered and the mother liquor re-cycled. Specifications 661,945 and 661,946 are referred to. |
| priorityDate | 1958-05-02-04:00^^<http://www.w3.org/2001/XMLSchema#date> |
| type | http://data.epo.org/linked-data/def/patent/Publication |
Incoming Links
Total number of triples: 30.