Local properties of filter cakes formed from pH-adjusted bauxite residue slurries

• Solid-liquid separation of bauxite residue is a topical issue in the alumina industry, not least due to the great quantity and problematic properties of this highly alkaline residue. The objective of this contribution is to provide deeper knowledge about the solid–liquid separation of pH-adjusted (pH 11) bauxite residue by investigating the local filtration properties of filter cakes produced with a piston press. Two bauxite residue samples having different particle size distribution were investigated. Measured local data of the hydrostatic pressure and solidosity was used together with flow rate data to calculate local specific filtration resistance as well as compressibility data. For the investigated pressure range (0.2–2 MPa) it was found that the residue formed slightly/moderately compressible filter cakes with a specific cake resistance between 5·1011 to 1.5·1012 m/kg. The sodium recovery and final cake solidosity were strongly dependent on the applied pressure, but only to a minor extent on the particle size reduction obtained by the applied mechanical treatment. The filter cakes formed from the mechanically treated samples did, however, display a somewhat higher pressure dependence for the local specific filtration resistance compared to the non-ground samples.

Ämnesord

NATURVETENSKAP  -- Kemi -- Analytisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Analytical Chemistry (hsv//eng)

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Livsmedelsvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Food Science (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

Nyckelord

Filtration

Filter cake

Red mud

Bauxite residue

Separation

Local properties

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)