Patent DE-19927907-A1 (DE)
Title: One stage high density sludge purification of acidic waste water from mining operations to remove uranium, iron, sulfate ions and other impurities
Inventor: SCHREYER JOCHEN
IPC: G21F9/10
Filed: 1999-06-18
Abstract: A process and apparatus are claimed for one-stage high density sludge purification of waste water from mining operations having pH 2-4 and containing metal ions such as Fe as well as up to 50g/l uranium or its products and up to 5g/l sulphate.  Purification by a one-stage high density sludge (HDS) method of water of pH 2-4 from mining operations and containing metal ions such as Fe as well as up to 50g/l uranium or its products and up to 5g/l sulphate comprises (i) adding a precipitating agent (6) and/or BaCl2 by spraying the water from a chamber (2) via nozzle(s) (3), operating together with an atomizer on the water-jet pump principle, into the first chamber (10) of a multichamber vessel (9); (ii) simultaneously feeding into chamber (10) the recycled washed ore sludge (5) which has been previously mixed in a conditioning tank (8) with the precipitating agent (6), the sludge stream and the contaminated water (aereated during its free fall) being held in chamber (10) for 10-30 minutes for Fe and Mn oxidation before overflowing in tube (13); (iii) feeding each chamber (10) with precipitating agent and aereated contaminated water and raising the pH stagewise in increments of 1.0-2.5 to 7.0-8.5 so that addition of BaCl2 to the vessel (9) causes co-precipitation of radium; (iv) effecting solid/liquid separation by adding flocculant in a stable suspension bed of metal hydroxide-gypsum in a high capacity concentrator (14); (v) recycling for more than 10 times most of the drawn-off sludge (16) (controlled by the sludge level (18)) to the process and renewing pH alteration by addition of precipitating agent (6) and mixing with contaminated water; and (d) directly disposing of the remaining easily dewatered inorganic sludge residue. There is also an Independent claim for apparatus for purifying acidic, Fe- and sulfate-containing waste water from mining operations by use of earthen or concrete vessels and a clarifier or round concentrator, the apparatus comprising a distributing chamber (4) above a partitioned multichamber vessel; a distributor (2) with one or more nozzles (3) with different lengths and of inlet : outlet diameter ratio 1.5-2.5 : 1; an atomizer on each nozzle with air inlet openings and/or internal atomizing lattice; a bank of \-2 aereating chambers (10) fed by the water-jet principle and of sufficient volume to allow the required dwell time; overflows (11) between the chambers; a narrow inlet tube (12) into a tube (13) which has a constriction just before its outlet end; and a concentrator (14) with cross-sectional area ratios inlet tube (12) (A0) : tube (13) (A1) : constriction (A2) : tube (13) outlet (A3) : concentrator (14) (A4) = 0.05-0.2 : 1 : 0.3-0.7 : 0.5-0.9 : 5-9, the upper slud ge level varying between 1.5m above the outlet of tube (13) and 0.5m below the clear water overflow (17) and the value of cross-sectional area (A4) of the concentrator being adjusted to the required through-flow for the plant.