In en:)l r-se a dashed line is shown to extend from the flux curve, as a tangent, to the feed flux used in the semi-continuous tests. 500 500 333 389 278 500 500 722 500 500 << This would be done by desliming the fotatio:: feed and sending the slimes to the thickener, Because the thickener was already heavily loaded, the effect of additional feed on the thickener performance was a major concern. /Image80 74 0 R endobj /S /Transparency 24 0 obj /BaseFont /ABCDEE+CambriaMath >> /Font << << /CS /DeviceRGB /CS /DeviceRGB 247 0 R 250 0 R 251 0 R 252 0 R 253 0 R 254 0 R 255 0 R 257 0 R 256 0 R 258 0 R /Tabs /S >> /XObject <<
<< 7. It is evident that as the feed flux of the test was increased, the resultant flux curve deviated toward the Kynch flux curve. >> 119 0 R 120 0 R 121 0 R 122 0 R 123 0 R 126 0 R 124 0 R 125 0 R 127 0 R 128 0 R /Slide /Part >> The diameter of the rakes was close to that of the internal column diameter and they rotated at only 6 rpm. >> /Group << There is a remarkable agreement between the continuous results and the flux curve determined by the concentration profile method.
>> /Resources << /GS8 40 0 R /Group << This is sometimes attributer: to rake action, but it can easily be shown (HassetW by material balance to be a natxral phenomenon, indepandent of the rake action. /F1 34 0 R /Tabs /S /F4 37 0 R 15 0 obj
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0 0 0 0 0 500 0 444 556 444 /F6 43 0 R 220 0 R 219 0 R 221 0 R 222 0 R 223 0 R 224 0 R 225 0 R 226 0 R 227 0 R 228 0 R /Resources << The thickener solids feed loading was estimated to be 48 tph. /Type /Group /GS7 39 0 R /Type /Group 25 0 obj
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19 0 obj Batch tests at initial concentrations less than 20 kg/m3 were not feasible, as the interface was unclear and the final sediment volume was very small.
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Typical concentration profile of the consolidation zone after time I: tration from C to Crnax is present at the base, at time T = 0. 17 0 obj /Encoding /WinAnsiEncoding 189 0 R 190 0 R 191 0 R 192 0 R 193 0 R 200 0 R 194 0 R 195 0 R 196 0 R 197 0 R
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/Parent 2 0 R /GS7 39 0 R Vessel diameters calculated using the three flux curve methods. >>
/Resources << Full width samples could be collected. /GS7 39 0 R
/BM /Normal 11 [170 0 R 171 0 R 172 0 R 173 0 R 174 0 R 175 0 R] /MediaBox [0 0 595.32 841.92] /ProcSet [/PDF /Text /ImageB /ImageC /ImageI] /Tabs /S /FirstChar 32 /Group << endobj /F3 36 0 R
/F5 38 0 R /Parent 2 0 R /F4 37 0 R In addition, the capital cost of a thickener will be dependent on the calculated required settling area. 0000007628 00000 n
/GS8 40 0 R The flux curve determined by the method of Kynch was obtained from batch tests at i.nitial solids concentrations of 20, 30, 40 and 50 kg/m3. /S /Transparency /Image61 62 0 R
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AdVticyoieif degnttmg I Table 3. /S /Transparency /GS7 39 0 R << /Resources << The remaining flux curves were determined from concentration profiles obtained from semi-continuous tests. >> >> /Widths [250 0 0 0 0 0 0 0 0 0 /ExtGState << >>
/ExtGState << /Type /Group /Type /Page An initial experiment was carried out on a sample of existing thickener feed and in another two tests, thickener feed was combined with mass proportions of 23% and 53% of minus 0.063mm flotation feed material. Although no additional solids are assumed to report to the thickener, tho overflow from the degritting cyclones would report to the thickener, contributiug a substantial volumetric flow which could have an effect on flocculant requirements to ensure adequate clarity of the plant process water (thickener overflow). /GS7 39 0 R /Image87 79 0 R The diameter of the existing thickener was 45m. 0000012294 00000 n /S /Transparency March/April 1937 Filtration & Separetlon.
1.
7 [133 0 R 134 0 R 135 0 R 136 0 R 137 0 R 138 0 R 139 0 R 140 0 R 141 0 R 142 0 R 0000003199 00000 n (1) it follows that V, = l/C VP dC 63) Therefore the settling velocity of the solids can be calculated if the velocity of propagation of each concentration in the range from C to Cm= is known. /ExtGState << /CS /DeviceRGB 0 444 0 722 667 667 722 611 556 722 /Font <<
<< >> -~@aa5l!)#"~ ?c ch_c sr8CQ!x?08-1|B1VqO^A`GP;z_)oT^zzD6 U285;L*NX.:.L%N _SRn:lb1X,jT4KE>JJf&M:30:,MBQu_}T;Y@# >> >> endobj 8 [145 0 R 146 0 R 147 0 R 148 0 R 149 0 R 150 0 R 151 0 R] This was in agreement with the observation that the effective feed fluxes of the batch tests used in the Kynch method were always relatively high. >> 0000010280 00000 n
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>> /Type /Page \ 0.06 profile Concentration flux curve \ Method \ B ;; 0.06 I \ \ Kynch \ 0.08 \ \ \ \ \ \ \ \ \ 250 Concentration 300 350 400 450 (kg/m3) Fig 8. /CS /DeviceRGB 14 0 obj /Type /Group /StructParents 0 H$"J}HI}r"meFdgL ztfD3=SUn=W}[nYJ2NjQ?a~+@aZ__$IxEhZ2U|i Xr_afB'4LQf4cIx9[_~_?jM)Wh0&IX*@)*im|Al@ ;}K6{;)Dx>xnm)S`4sVQzf7,.rttJYX^eB'pM{qOe~}3T8"`Y9Z8){hDd6S'w[S3m|`
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/Contents 47 0 R It is employed mainly in design calculations to determine the required thickener area, the most important design parameter, and ultimately the maximum steady state underflow concentration that is possible for a given solid throughput. 14 [192 0 R 193 0 R 194 0 R 195 0 R 196 0 R 197 0 R 198 0 R 199 0 R 200 0 R] %PDF-1.3 % endobj /Parent 2 0 R /Type /Page << /GS7 39 0 R /Parent 2 0 R << 0 the process is one-dimensional and so there is no radial variation in concentration for any horizontal layer Cl the slurry can be treated as a continuum, with a continuous liquid and solid phase interacting with each other In the sedimentation of a slurry there are three important velocities. The flux curve determined by the Kynch method was therefore invalid for systems at the much lower feed fluxes typical of industrial practice. /GS7 39 0 R /S /Transparency This is a significant limitation of the model. The height of this interface is plotted as a function of time and a batch settling test curve, similar to Fig 3 will result. 16 0 obj
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However, it is evident that a 25% reduction in underflow solids is likely for cases 2. >>
18 [221 0 R 222 0 R 223 0 R 224 0 R 225 0 R 226 0 R 227 0 R 228 0 R 229 0 R 230 0 R] Flltretion&Seperetlon Flg 19. /Group << endobj /CreationDate (D:20200528201915+05'30') Fig 6 shows the bed height and underflow concentration as a function of time and the final concentration profile for one of the continuous sedimentation experiments. /Group <<
The slope of this line is equal in value to the underflow velocity and the line is a tangent to the solids flux curve. /ParentTree 32 0 R >> /ExtGState << The solids flux curve was found to be dependent on the solids feed flux into the system. /S /Transparency
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the resultant flux curve approached that obtained by the Kynch method. It was also assumed that all of the coarse tailings would report to the cyclone underflow - hence a best case scenario was assumed. >> <<
trailer << /Size 30 /Info 2 0 R /Root 4 0 R /Prev 13617 /ID[<54e7d34982f32c490f4ba6fe4c249a48><54e7d34982f32c490f4ba6fe4c249a48>] >> startxref 0 %%EOF 4 0 obj << /Type /Catalog /Pages 1 0 R >> endobj 28 0 obj << /S 36 /Filter /FlateDecode /Length 29 0 R >> stream >> Consequently Fig 5. Flltration & Separation March/April 1991 SOClElV the Kynch method was restricted to effective feed fluxes greater than 0.14 kg/(m2s). /F4 37 0 R and Clevenger, 2.
>> 7 0 obj /FirstChar 32 After a time T, the bed was sampled, to determine the concentration profile and hence the solids flux curve by the new experimental method. /Type /Page >> 113 PROCEEDINQS OF THE FILTRATION SOCIETV 0.1 0.1 \ i z \ z ,I I 0.08 Operating lines from thkkentng % g continuous z x i 2 u 43 -3 0.04 g z i. The difference between the flux curves determined by the Coe and Clevenger, and Kynch methods is similar to that obtained by Talmage and Fitch. /Parent 2 0 R The other limitation of the principal assumption is that the effect of bed height on underflow concentration cannot be assessed. Predicted steady underflow Volumetric Rate (m3hr) 26 19 160 343 20 254 state underflow percent rates for the thickener.
104 0 R 104 0 R 104 0 R 104 0 R 104 0 R 104 0 R 104 0 R 104 0 R 104 0 R 104 0 R /Endnote /Note
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SOCIETY >> /F4 37 0 R -0.063mm 160 Iph - 56 Iph Desliming CyCl*fle Flolatlon Yield 85?h 88 Iph Filtration of concenlrate I 56 tDh Tailings Disposal 16 lph Disposal with Coarse coal lb*)51 Fig 11. /Contents 57 0 R /Image50 55 0 R /MediaBox [0 0 595.32 841.92] A clear interface should appear between the slurry and supernatant. /Contents 88 0 R A discussion of the reasons for this can be found elsewhere (Galvin and [emailprotected])).
Experimental Procedure Figure 4 shows a diagram of the equipment used in the batch and continuous experiments. 0 389 0 778 667 944 722 778 611 0 /Resources <<
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11 0 obj /F5 38 0 R This March/April 1991 desllmlng flowsheet. Case 2. would result in the volumetric underflow rate increasingby about 115%.
Eed height and underflow concentrations as a fUnCtiOn of time and concentration profile at 100 min. endobj
>> /Image23 41 0 R The vessel had an internal diameter of 95mm and the wall of the vessel contained sampling locations at heights of 10, 50, 150, 225,300,600,900 and 1200mm for obtaining samples to determine the concentration profile. /MediaBox [0 0 595.32 841.92] 99 0 R 100 0 R] 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R 102 0 R
>> /Group << >> << Be, Vehicle Dynamics: Theory and Application /Tabs /S /GS8 40 0 R The operating lines, drawn from the underflow solids flux on on the flux axis, to the corresponding final underflow solids concentration on the concentration axis, are shown in Fig 7. The method of Kynchs) enables the solids flux curve to be determined from a single batch test. 20 0 obj <<
3 0 obj /GS8 40 0 R t!iFe solids flux curve model can be used to predict th& underflow solids concentration for any underflow rate, as well as the rise velocity of the bed for non-steady state conditions. >> /Type /Page
endobj The solids flux curve is used to model the process of continuous sedimentation. /Font << 198 0 R 199 0 R 201 0 R 202 0 R 206 0 R 203 0 R 204 0 R 205 0 R 207 0 R 208 0 R
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Sizing analysis showed that 35% of the flotation feed was less than 0.063mm. /Type /Font /Group << /Type /Group /Contents 80 0 R 12 [176 0 R 177 0 R 178 0 R 179 0 R 180 0 R 181 0 R]
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Address: Copyright 2022 PDFCOFFEE.COM. /Font << Exlstlng 88 tph Fillration of concentrate flowsheetkr fine coal treatment. Learn how we and our ad partner Google, collect and use data. >> That is, V, = l/CT HdC (10) By determining the area under the curve in Fig 2 between C and Cmax and dividing the result by CT, the settling velocity of the solids, VS at concentration C can be found.
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/Parent 2 0 R >> Validation of the Solids Flux Curves Using Continuous Tests. Current operation 2. /Font <<
This velocity is superimposed on the settling velocity of the solids, resulting in a total velocity inside the vessel, and relative to the vessel, of VS + Vu. 34 0 obj /CS /DeviceRGB /ExtGState <<
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(3) Solids Flux Curve Model Predictions and Validation. >> /Width 640 /Resources << Batch Tests. 18 0 obj
/StructParents 1 >> A high molecular weight anionic polyacrylamide flocculant 1?2 - - B -2 Pluger Ba~;hs+~etting c (Column Height 1.5m) Cantlnuous - Underf L(w Pump) ( Perataltlc Thickerung Kolumn Height 30m) Fig 4. >> >> /F4 37 0 R
In the continuous tests, the bottom sampling tube was connected to a pump and underflow was removed at a constant rate from the start of the experiment, The underflow concentration was determined by collecting samples at regular time intervals. /ProcSet [/PDF /Text /ImageB /ImageC /ImageI] /ExtGState << As shown in Fig 3, after a time t = T, the height of the interface will have fallen from a height of HI to a height H and the concentration just. Design and Operation of Continuous Thickeners, Ind. and Fitch, E.B., 1955. /ExtGState << The effective feed flux is equal to the mass rate per unit area that solids settle through the discontinuity and into the sediment.