Válasszon nyelvet:
A.Gupta, K. Flynn és F. Edit
ST berendezések & Technológia, 101 Hampton Avenue, Needham, MA 02494, AMERIKAI EGYESÜLT ÁLLAMOK
Absztrakt
ST berendezések & Technológia (MEGHAGY) is the developer and manufacturer of triboelectrostatic belt separation system that provides the minerals industry a solution to beneficiate fine mineral ores by using a dry technology. The triboelectrostatic belt separation technology has been used commercially to separate a wide range of minerals including calcite/quartz, talkum/magnezit, barit/quartz, and aluminosilicates/carbon in fly ash. The high efficiency multi-state separation achieved by particle to particle charging results in superior separation as compared to a conventional free-fall triboelectrostatic separator. It is a dry technology and doesn’t require use of environmentally sensitive chemicals and water, hence no waste water treatment systems are required in the process. In this report, results of a successful pilot plant scale beneficiation test conducted on a mixture of zircon/rutile in mineral sands are published.
Kulcsszavak: Ásványi anyagok, szárazelválasztás, triboelektrosztatikus töltés, elválasztó öv, mineral sands, zircon, rutile
Bevezetés
STET triboelectrostatic separator utilizes differences in the surface chemistry between the particles of the feed material to create electrical charge differences. When two dissimilar surfaces are rubbed against each other, charge transfer takes place with material with lower electron affinity losing electrons to the material with higher electron affinity thus charging positive and negative respectively.
In STET triboelectrostatic belt separator, feed material is fed into a thin gap between two parallel electrodes. There is an open-mesh belt moving between the electrodes at high velocity, upto 65 feet/sec, forming a loop around a set of rollers on both ends (Ábra 1). The particles are triboelectrically charged by the vigorous particle to particle contact and are attracted to the oppositely charge electrodes. The belt sweeps the electrodes and carries the different particles to opposite ends of the separator. The counter current flow of the separating particle and continual triboelectric charging by particle to particle collisions provides for a multi-stage dry beneficiation process. Az elválasztó tervez viszonylag egyszerű és kompakt. The overall length is approx. 30 Ft (9 m) and width 5 Ft (1.5 m) for a full size commercial unit.
STET maintains a research and development laboratory at the STET technical center in Needham, Massachusetts. This facility includes the STET pilot plant and chemistry laboratory, as well as the design, manufacturing and technical support departments for STET’s business development and manufacturing facilities. The pilot plant houses two reduced scale, STET separators along with ancillary equipment used to investigate modifications of the STET process and to evaluate the separation of fly ash and minerals from candidate sources.
Ábra 1: STET triboelectrostatic separator schematic
Mineral sands
The mineralogy of rutile reject sample was approximately 41% rutile, 33% zircon, 18% ilmenite and 8% other minerals. The objective was to establish processing conditions to recover zircon from the rutile reject sample. STET conducted chemical analysis using wavelength dispersive X-Ray fluorescence (WD-XRF) on feed sample and the results (normalized for LOI) are shown in table 1.
Táblázat 1: Elemental analysis of mineral sands sample (major components shown)
Conventional methods for beneficiating mineral sands involve complicated flow sheets using processes such as wet gravity techniques, magnetic separation and froth flotation (ref. 1,2) which have their own limitations. The magnetic separation process often leads to a middling fraction which require either disposal or recycling back to the feed stream. Magnetic separation using rollers have other limitations in processing fines. The fine particles, even non-magnetic tend to form coatings on the roller, rendering the separation process ineffective. STET separator is well suited for separation of very fine materials with very high throughputs. Wet gravity and froth flotation processes involves heavy wet chemical and water usage, and requires waste water treatment process. For dry final applications, a drying step has to be added downstream of beneficiation step thereby increasing operating costs.
STET’s triboelectrostatic technology provides a unique capability to process the feed dry, with low electricity consumption, typically approx. 1 kWh/ton (ref. 3) and generates two upgraded streams on either end of the separator with no middling fraction.
Eredmények
STET demonstrated evidence of effective charging and separation of zircon and rutile mineral particles. It was seen that doping the feed ore with small quantities of aromatic or aliphatic carboxylic acids (electrostatic charge conditioning agents) showed significant improvement in the separation behavior. Ábra 2 below shows product grade (ZrO2 content measured using WD-XRF) and ZrO2 recovery to product for all the runs conducted at STET pilot plant. It can be seen that under optimized conditions with feed doped with aromatic carboxylic acid at 2000 gm/ ton dosage and moisture, product grades of >50% ZrO2 content with >50% ZrO2 recovery to product were achieved (see highlighted data). Average ZrO2 content for the feed was approx. 30%.
Ábra 3 shows by-product grade (TiO2 content measured using WD-XRF) and TiO2 recovery to by-product for all the runs conducted at STET pilot plant. It can be seen that under optimized conditions with feed doped with aromatic carboxylic acid and moisture, by-product grades of >50% TiO2 content with >80% TiO2 recovery to by-product were achieved (see data highlighted). Average TiO2 content for the feed was approx. 40%.
Táblázat 2 below shows the results from runs conducted under optimized conditions. STET was able to achieve >50% A termék jobb cirkon tartalom beneficiating a takarmány átlagos ZrO2-tartalom 30% ZrO2-tartalom. A rutil töredéke a takarmány gyűjtötték, mint melléktermék, a >50% TiO2 tartalom beneficiating a takarmány átlagos TiO2 tartalom kb. 40%. Jövőre fog összpontosítani optimalizálása a szétválasztás eredményeit csökkentésével a dózis ingyenesen kondicionáló szerek.
Ábra 2: Pontossági fokozat (ZrO2-tartalom) Varga/helyreállítás (menetben eredmények)
Ábra 3: Osztályos melléktermék (TiO2 tartalom) Varga/helyreállítás (menetben eredmények)
Táblázat 2: Optimális feldolgozási paraméterek segítségével "rutil elutasítja" feed alatt elért eredmények
Következtetés
Ez sikeresen bizonyított, hogy STET triboelectrostatic öv elválasztó képes hatékonyan beneficiating a cirkon/rutil keveréket tartalmazó ásványi sands feed, ami kiaknázhatóvá frissített cirkon, rutil és tartalmának a termék, és melléktermék, illetve. Ezt a technikát nyújt költséghatékony, életképes alternatíva, és esetleg megszünteti a nedves feldolgozási technikák. A környezetvédelmi szempontból érzékeny vegyi anyagok vagy a víz használata nem igényel, és következésképpen nem tesz szükségessé, valamint a végső anyag szárítás. STET elválasztóként energia fogyasztása alacsony, kb.. 1 kWh / tonna feldolgozott takarmány-alapanyag.
Referenciák
1. RUDOLF. Tyler és R.C.A.. Minnitt. A felülvizsgálat a szub-szaharai nehéz ásványi homok betét: következményei az új projektek, Dél-Afrika. A Journal of a Dél-afrikai bányászati és kohászati, 89-100, Március 2004.
2. V.G.K. Gábor, D. Tünde, S. Airizer Mária és A. Chatterjee. Indiai nehéz ásványi homok – néhány új lehetőségeket, Tata Steel azonosított dúsítása. Eljárás a nemzetközi szeminárium a dúsító technológia, 2006.
3. JENEI TAMÁS. Bittner, KEDVES. Flynn és F.J. Edit, Bővülő alkalmazások száraz Tribolectric szétválasztása ásványi anyagok. Proceedings of International Mineral Processing Congress, 2014.
