Valmet Ab

Valmet Power Ab

Valmet Aktiebolag

Martin Wimby

Henrik Wallmo

Per Tomani

Fredrik Öhman

Peter Björklund

Anders Littorin

Mattias Svensson

Lars-Erik Åkerlund

Hanna Kristina Karlsson

Hanna Karlsson

Fredrik ÖHman

Lars-Erik ÅKerlund

Joana Nunes

The method is for separation of lignin from original black liquor (BL) having a first precipitation phase (PR1/PR2) for precipitation of lignin by a first acidification using acidifier, CO, at alkaline conditions, then separating a lignin cake with subsequent suspension of the lignin cake in a strong acid to leach our metals from the lignin followed by dewatering and obtaining a clean lignin product LP. The acidic liquid phase (FL) subjected to a sulphur removal process wherein a calcium containing compound is added to the acidic liquid phase, whereby sulphur in the acidic liquid phase is reacting with the calcium compound forming solid gypsum which could be separated and bled off from the process. The remaining acidic liquid could then be returned to the recovery process without negatively affecting the sulphur balance of the mill.

Method for lignin separation from black liquor comprising removal of sulfur compounds from formed water effluent

The method is for separation of lignin from original black liquor (BL) having the following phases in sequence; a first precipitation phase (PR) for precipitation of lignin by a first acidification of the original black liquor by adding a first acid or mixture of acids (G); followed by a second precipitation phase (PR) for precipitation of lignin by a further acidification of the original black liquor by adding a second acid or mixture of acids (G). The first phase is implemented to lower the pH while avoiding any larger amount of precipitation, i.e. less than 2-5%, while the second phase is implemented in order to obtain the larger part of the precipitation. In total is 40-70% of the total lignin content of the original black liquor precipitated while the residual black liquor after precipitation is still strongly alkaline.

Method for lignin separation from black liquor having multiple acidification steps

The method is for separation of lignin from original black liquor (BL) and has the following phases in sequence. A first precipitation phase (PR) for precipitation of lignin by a first acidification of the original black liquor by adding a first acid or mixture of acids (G) followed by a first storage phase wherein precipitated lignin particles are allowed to increase in size, followed by a second precipitation phase (PR) for precipitation of lignin by a further acidification of the original black liquor by adding a second acid or mixture of acids (G). By retaining the acidified black liquor for at least 25 minutes in the storage phase are the precipitated lignin particles allowed to grow in size and the filterability is improved considerably.

Method for lignin separation from black liquor involving multiple acidification steps

The method is for separation of lignin from original black liquor. Lignin is precipitated in a first acidification stage followed by dewatering a first lignin suspension while forming a first filter cake. The first lignin filter cake is suspended in a second acidification stage whereupon a second lignin suspension is obtained. The second lignin suspension is dewatered to form a second filter cake. The second filter cake is washed and the washed second lignin cake is dewatered to obtain a lignin product. Waste gases from the second acidification stage is recirculated back to the first acidification stage and mixed with the original black liquor.

Method for precipitating lignin from black liquor by utilizing waste gases

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Torslanda, Sweden

Martin Wimby