Procedure for filtering lime sludge meant to be regenerated to lime
US4687583A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 1986 |
| Grant date | Aug 18, 1987 |
| Priority date | — |
| Expiry date | Mar 12, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/928
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
In a procedure for filtering lime sludge meant to be regenerated to lime. Lime sludge is produced in the causticizing process in a sulphate cellulose mill, where it can be reused after regeneration to lime. In the procedure, lime sludge suspension is filtered on a filter drum in continuous rotation by depositing lime sludge on the drum and detaching part of the superficial layer of the lime sludge on the drum with a scraper so that the deeper lime sludge layer on the drum, which by-passes the scraper, serves as filtering medium for the superficial layer that is detached (as a so-called pre-coat). The purpose is to arrange the control of the filtering process so that the dry matter content of the lime sludge detached from the drum is substantially constant, and its essential feature is that the dry matter content of the lime sludge detached from the drum is followed so that when the dry matter content tends to decrease, the speed of rotation of the drum is first raised within a given control range and, after the control range has been used up, the scraper is moved closer to the surface of the drum so that at least part of the deeper lime sludge layer on the drum, serving as filterin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.