1994-02-28_REVISION - M1988112 (2)

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82 ~' MINQVG AND MINERAL. PROCESSING WASTES the difference between thaw values (Sobak at al., 1978) os ~:hs it ratio (Caruccio et al., L980). Analya:La of solid phase charatteriatics such ae th era can ba done relatively quickly and at low coat, but they do not provide the rates at which ac Sd :Ls producad~or neutralized. the r.3tes of at id production and coneump- tlon can 6e ad<Ire ssed Ln kinetic testa. These tea [e era typically more expene ive and time consuming 'Chan static [eats. Detection of acid generation of [::x .an Snit ial lag period requires an extended period of experimentation (Had in and Erickson, 1988,. Mille[ and Murz ay, 1988). Erroaeoua concl.ue tone could be draw based se ricely on the drainage quality observed during the Ce9[9. Neutral drainage could be observed over the rule tl.vely shore duration of the tee[ but, over a longer period in the field, Che aeutrellzat:ion pa [tent Sal could depleted with resultant dra icagn ac ldiF icaClon. Thus, [he rates of acid procluc[ion and consumption can ba determined frox kinetic teats, but St may be time consuming co experimentally determine if the acid neat ralir.Sng capacity will be depleted before the acid producing capacity. To determine the potential for some mine vaetee to produce acid drainage SC ie neceaeery co quant Sfy the tlmea requlced to deplete the ac ld producing ircn gulf idea and the acid neutralizing mine vale. The following study vas undertaken to as ae ae the feasibll icy of each quant if icat lone far refining mine waste drainage quality pred Sctioae. METHODS Materials Ainetic expe rimert[e vere canduc[ed on mixtures of rot.iry kiln fines and rock using a vet-dry cycle of one week. Aotary kiln fines are a waste product generated when limea[ana Se converted to Lime, and vere ob[aiaed from Che Cutler-Magner Cnmpeny fn Duluth. Chemical and particle size analyses of these solids era presented in cable 1. Table 1. Chemical and particle size analyaia of AIC floss. Values in Percent passing weight percent by weight Ca0 35.9 LOI1 26.37 4 mesh 100 Mg0 1.1 n12U.1 3.71 20 mesh 99.97 Hn 0.03 Fe20} 2.63 200 mesh 96.74 !Lose on Sgnit ion the rock used vas from the Duluth Complex Sn northeastern Minnesota (drill core temple 755-1338), the plus 10 mesh fraction of minus 1/4 inch drill core raj act vea at:ags crushed using a pule erizar and vet-screened to segregate the -100(+270 fcactlon for use Sm [he kinetic testa. The sulfur, capper, nickel, cabal[, and zinc can [tote of [h!e fret[ ion vere 2.1, 0.11, 0.053, 0.007, sad 0.069 percent, respectively. P laginclaee, oily lne, pyrox toes, Sad b1oClte v.: re [he predominant mineral o. A mass o: 0.189 g RK fines vas added to /i I; of rock, producing an alkaline so Lid:aulfur ratio of 0.5:1. :n order to thoroughly blend the alkallme solids with the rock, the alkaline solids/rock mlxturse vere peened through a sample sp litter 10 times. The sulfur content and [he neat raliz atioa potential of [he r~~ck and RK fi~aes vere determined, and the aeaociated values for [he mixture vere calculated. Table 2. Sulfur content and NY of rock, RR fines, and the mixture. Ratio ZS App N4 Rock 2.1 65 11 RR fines .03 1 755 Hlzture 2.08 65 k1C a,¢ Procedure Several tech ntque• have been uaad in labora~- cory leaching aE mining vaetee (Caruccio, 1986; Fe rguaon and Ma:z.ling, 1986). Tha method uaad vas based on the prLneipl• that sulf lde minerals oxidize in the ~p reaene• of atmospheric oxygen and water (Gott •eha Ll[ and Bushier, 1912; Caruccio •tt al., 1980). That axpsrlasnte vase conduetsd in units deaignad :o parmlc ehs rinsing of eolida and filtrst iom Sri the rinse talus Lon in one et ep (U.S. Patent No. 4,783,318). the mixtures vere placed onto a l.~i micron Whatman CF/A glass fi~oer filter (5.5 cm ~i:Lameter) which ce•+e red a pleat Lc plate In Che upper section of a two-stage filter unit or reactor. The reac BOre tad ealtde ware scored in a boat to dry and ozid:L::e. A .cover vas placed about i cm above the upl~nr edge of the box to allw drying of th• eo:lid• and prohibit ih• input of airborn debris. A the rmoetatltally controlled heating pad vas ),laced beneath eho be: to mein~- tain a constant temperature. Yatar containers were placed in tl,a box, and • humidifier and dehumidif ire watt:: placed in the room, in an attempt to maint::la a fairly constant humidity. Temperature and to letivs humidity in the box vie re monitored four to five times per weak. the temperature rani;nd from 23 to 32 ~~C. with a mean of 26.7 °C and .t standard day iation of 1.55 °C. Relative humldit~. ranged from 18 to B3 percent, with a mean of :ili.l and ^ standard deviation o:E 10.6. The eolida vets rinsed weakly vtth 200-mL va lumen of diae:L:.led deianixed water. The 200 ,eL