SE543503C2 - A method of producing a low ash content biofuel mixture comprising tall oil pitch and lignin and uses of the biofuel mixture - Google Patents

Abstract

The present invention concerns a low ash content biofuel mixture comprising tall oil pitch, lignin, and optional additives. The biofuel mixture is obtainable by:- providing a stream of TOP, thermally treating the stream of TOP in the presence of water or steam and purifying it;providing a stream of lignin purified having an ash content below about 0.1 %; mixing the low ash lignin and the TOP in a reactor; anddischarging a pumpable and substantially homogeneous low ash biofuel mixture comprising TOP and lignin from the reactor.The obtained biofuel mixture may be used as a renewable feedstock in petroleum refineries, as a biofuel for power and/or heat generation, as a fuel for limekilns or kilns for iron ore processing or as a feedstock for fine chemicals or carbon fiber manufacturing.

Description

. - . = - . i “A IVÉÉETHQD ÛF PRÜÜUCÉNGA ísiiïwïf' .ÅSH (QÜNTENT BHÉÉFÉJ Å/ÉEXTEIRJÉ CiÉÉMPRT-SENåÉ TAJJI.. Uli.. PÉTCHJf-XNI) ÉÅÅÅENÉNT fXNí) TÃISÉÉÉS íÅššÉf Tšfííšl lššš ßf) šïï_í ššiï_t ïxffíïXïlšglRíšl ..: '__' _: -. ; U- ' ' ~-. ' 'Å Field of the inventionThe present invention relates to a rnetliotí 'for produciiia: a Iowa' ash :zontent bíofucl mixture atofiifsrïflsirvf* ešštall oil pitch (TOP) and lignin.

Technical BackgroundLignin is a class of complex organic polymers that form key structural materials in the support tissues of vascular plants and some algae. Lignin°s are particularlyimportant in the formation of cell Walls, especially in Wood and bark, because they lendrigidity and do not rot easily. Chemically, lignin”s are cross-linked phenolic polymers.Lignin is liberated in the traditional kraft process and discharged from the kraft digesterin the form of an alkaline liquor called black liquor. The black liquor is an aqueoussolution of lignin residues, hemicellulose, and spent inorganic chemicals used in thepulping process. Lignin may also be liberated from Wood or nonWood lignocellulosicplants by other processes than the kraft process such as the sulfite process, organosolvor hydrolytic processes. The lignin obtained is therefore often referred to as kraft lignin,sulf1te lignin (or lignosulfonates), organosolv lignin or hydrolytic lignin. Kraft lignin isdominant source for lignin for a foreseeable future, the sulfite processes are declining,organosolv and hydrolytic lignin is available in minute quantities only as theseprocesses are still only operating in pilot scale. Kraft lignin extracted from black liquoris potentially available in tens of millions of tons per year. Most kraft lignin is bumed inthe kraft pulp mill recovery boiler for raising steam. Recently technologies forextracting kraft lignin from black liquor have been commercialized. These processes arebased on acidulation of the black liquor With acids and subsequent recovery of lignin byfiltration as exemplified by disclosure EP2247785. Another route for recovery of ligninis based on membrane filtration and subsequent Washing of the lignin by acids and/orsolvents. Such method is disclosed in SE 540451 included here as a reference in itsentirety.

Tall oil pitch (herein after TOP) is an oily by-product obtained When processingof crude tall oil. Crude tall oil is obtained from the black liquor of alkaline digestion ofconiferous Wood, most notably the kraft process. The black liquor from the kraft processis typically concentrated and settled to yield soap skimmings that contain sodium salts of fatty acids, sodium salts of resin acids and unsaponifiables (sometimes referred to as neutrals). The latter group of substances include fatty alcohols, free sterols, steryl esters,and fatty acid esters. In kraft pulp mills, the collected soap is routinely acidulated with amineral acid such as sulphuric acid to yield an oil phase and an aqueous phase. The oilphase contains free fatty acids, resin acids and unsaponifiables; it is commonly knownas crude tall oil. Typically, the amount of unsaponif1ables can range from l0 to 35% byweight of the crude tall oil, depending on the species and quality of coniferous woodused. The water phase containing sodium sulphate and any lignin entrained in theoriginal soap is norrnally recycled back to the pulp mill chemical recovery system. Inthe subsequent recovery of desired fatty acids and resin acids, crude tall oil is typicallyeVaporated under low pressure conditions to yield a light phase, known as depitched talloil, containing mainly fatty acids and resin acids, and a heavy phase, known as tall oilpitch (TOP), containing a substantial amount of the original unsaponif1ables. The TOPalso contains Varying amounts of fatty acids (straight hydrocarbon chain ranging fromC12-C26 of varying unsaturation degree i.e. zero, one, two, three, etc. double bonds andcontaining primary/terrninal carboxylic acid group) and rosin acids (typical examplesbeing Pimaric, iso-Pimaric, Sandaracopimaric, LeVopimaric, Palustric, Abietic,Dehydroabietic and Neoabietic acids occasionally referred to as resin acids) as well astheir deriVatiVes~. TOP is typically characterized by having a high Viscosity. TOPnorrnally also contain a considerable amount of ash, in particular calcium compoundsand sodium ash compounds such as sodium sulfate. The ash of an untreated TOP variesdepending on the source of crude tall oil and efficiency of upstream desalting steps, butis norrnally in the range from 0,l % up to 2-3 % by weight of TOP.The TOP residue fraction represents typically between 20-30 % by weight of CTO processed. The TOP typically has an acid Value in the range of 30 - 60 (mg KOH/ g) and already comprises a significant amount of Valuable carboxylic acids intheir free acid form. However, even larger amounts of these Valuable components arepresent within the TOP as carboxylic acid derivatives i.e. as in their bound form, suchexamples but not limited to are fatty acid steryl esters, fatty acid esters with fattyalcohols, etc.

The present inVention is directed to a substantially homogeneous low ash content mixture of TOP and lignin that can be used as a renewable feedstock in petroleumref1neries, as a biofuel for power and/or heat generation, as a fuel for limekilns or kilns for iron ore processing.

Summary of the invention According in a first asyfiafet; there år; erevšdfed. :x n1e;ï,'r10<.í för nrødxuafxinß: a Éevv ashezorfteïlt 'niofueí míxïure cernørisåtïg wii eíä Lwíïaïfz. (ÉÜPE ii and eïïïionaí adfííiiflzes.

The methecí conanrises the feiioxwfirv stans: - ïßrexfíaíínff a sïreanï efTGP; - thefinwai Ev fltreatšmf ïhe sï1:'e.afn.eí"TÜP .in 'fbe ïsreseïmff: eí"\>wa.í'f:r er steam: and*nurífxfínß- 'the stffezirr1øf'ï()P ie ßres/íde :ëuråfied TifišP ævífl: an. ash centers behöva 0.1 *ï/š;and deereesed xfíscositzf: - xerovidingf sïr-:ë-arn Qíforazaxízaxseíwf iivnin íwaïrfxíxfïic lívnín of eurifieaí kraftlixznin saíaí Éi< min Éurafirix: an ash eerxíient bešew 0.1 'ïÉ/e. vafnerein flïfne iigznin, bas beenmm' Fed ba* fme of zaeicä refínårïq xxfštš: an acid. seiveïxi extractien.. m” seívenï dissehaïionte r-:frnoxfe ash frem àhe iíßnin tf; a íevei behöva 0.1 945: - mixing flïæ xeurifieá lívnín and the gfilzifífied TOP sfvíth deer-iëz1s-zëd xfíscesiïxf in areaeíier; the prenørtšen. beiraweeïz Éifønii: and Tífš? being fiiern H) *V5 Éizfnin un in 90 %ííïgnín ffeíatixae m 'ÉÜ'()P; and - cíšseharging a numnaiàie and ïïixmeçíeiïeeias ifnf* ash 'ít-šffñaei rnšxture cernnrisin 51TU? and lkfnín íïoan flfæ reacter.

.According in anether aspeczt. ïhere is nrexfíded för :ase eí-'flxe iíaerebzf ebtaífaed'íëíofueï míxture as a renewabíe feedsàeck in 'netrfxšeaanx reífínreries. a bifxñxeš for :sevaer and/er heat aenfi-ratien, as a fuel für Éirn-:fkiíns 01' kišns far Åren ere nreeessínfl", G1' as a fzëefíswxiïíx fin* fine eheïníafiaís m" czlrbon fibeï manufaeïuïírxg. 'i *e " ef: *ertert Üeßuzï f. š -i 1» w wxmw' än - 5.- H "i R--J fy ä i; så' .n -l x-.x-š 1.11 få iš-Fx- . ..1\«~-. »4-1 11 1 ii-uxxmuux w mxxxxqexm ns. :ME n. m: x : k x, .vu nu» :xßxmxn nxxxu. vyux nu). »Jhxxcxux v ß vxxwxw .vxx _. u v] m: Aê.š'š'lffäzi¿í§ï'ïåëïf fxmøfdufiv '_ ff' an? F få? «w-~\ -Višn- f. w-wew vïiš flš-w áf-fäif. Jfi-:fl (nii ,xxx_ øx-xvß xu xnxxxy xxx ixwxr; ßxxxx w» f' wrï- iv 1-1. vi' w ni-xr-a' 1-1 1\ ~ :fi 1 4- Û fiï 0/lJxJ-vx. Å: 44/1) »axx u-øn vmvxxcyxn. U u, n vnuxfiux . 501 /U n>š~§»v\-i.-\-».--«1\Ešn- š-\ .- É"í“í'ï!l': 'n f; -,«.-f>n+,-- »w-(xí-“fx .-E lv -\°- R-f- i f» -wiq '° »fwLxxu\xxlá) xxxv mJxL :Lfbxxuxl x ,4 _: _.>x. xu. u. L wwx. n, isxxvxvx x x) xxLx.>\x.LxC L\xv ,_Lx Lxóxlxlx f-Yrn iv» »Ä 'w n» .fx-w-n-x: n. ky w f :wrï f» ~« w-í-Ü' 4.- øf « “vi "Pfïïš 'w n f» f' +f\ 5.1! w -fxfï 'i w»uxo: xv x xx x Vxbux v x. x x aux w -L x x xx u. x x x u, w -L x x x x .fd x iv. , f. “fw f n 4 +h^ <~ _- fiflx fi- i »mur 1 < « m i f farm»<.~\ X LL .x Fx L; V F 6 1A1x3\, 5 x R Ut; x 'X Rx i -12 ~ »i- .--,-- 'fl- f www. fï» i- fy ä ~ -w-f wffi-iï i- -vnia xx.cavx,'_._,rxtx.,;_,r »v Mxuxí. -M/:v -mxu ßßux_-k.cwx.:\.x.ca.cxd u. :ax v -nw ïw f .ud-x i» W-"xiå -xx Umm :U u» x: xuxm x »vx vf: .-x :xx .gu - vw» 'ff x x- ”EYÄB :vx/Å EJ »ds -if »vx fin). v-fwvs- »v f-vw. - v» -P--fv-»I fêš--x-.ï n» š-\ .- xaxixxexxnš, u ._ x uxfix. :xšyuxxl x.x xlx uxlv l vx. x xx: xxlmxx» kx x L: u» un) xxwx. Lx: xvn n vwï En m A w E~.««+,w«+'f.íi fi v» .- <4 1 v. “i 1 1i, i xí/w .f u w x x; i o 'L x 'Lx x] x i x fb x x! n. exuxxv ïfvfiwffïåï' -fš .¿+1«.- “vfèïmflfl-wflf â-m +i«»\ ~ n w <-Lv vMRÅ/b A1 i 4 i Cailšvšrlk, LR.\\/1^§\/~F -win-'f k; 5-2 ïy-švx-~-x.~fx-y-x.fï»ï 57' I-.i -iš +-,--i- wxw-.Wfl yš~n~fMNLUE 1.:: - vtxztu. t u: :Amuxy u-Qv v. : u. v x. x .L - mur. f: xx: xxuxvuxx: : :xxx x :Nos vz-._ »v '1-2 (-2 1-143- w- , V-f-n-lï-vï 11+ »ff n .-.-. .- -Fxfxl (7 »FW ï--šïvw »i 'i w (3 -fš .«\« »-L/:\xr.v..x L x. x k svvx. xu. x \)l xxvwx. \.~xx\.~x.wx.x\)1.x_¿, k w xuvx .L\:x xxLxxvxxxxJxo x x xx» L\)L xx .xl x fl n w--š- f- »w <1 f Cnqåiw» i f. få'*xx v o; x x so x v x 414-*2 fi- »- .-«'E ~.1f\¥"i~x»-1«nfwn+"= -+ »-<'«.--kcnx. di. vxxx x« x xwx-,\!vx xxx, x xx..xx 14x73, Further details of the Invention According to one specific embodiment of the present invention, the originalTOP and components therein has an average molecular Weight substantially above 350g/mol, e. g. in the range of 350 - 800 g/mol, and any fatty acids and/or rosin acids,and/or derivatives thereof, and/or unsaponif1ables and their derivatives present in theTOP have an average molecular Weight below 350 g/mol, such as molecular Weight inthe range of 200 - 330 g/mol. The latter compounds may be separated by fractionationprior to use of the residue TOP as blending stock for lignin. Ihe therrnaltreatrnent of TOP is perforrned in the presence of Water or steam. It is important to keepthe TOP hot at all times as viscosity is a direct function of temperature. The TOP is keptat a temperature above 100 °C and preferably at a temperature over 150 °C at all timesduring processing in accordance With the invention. Ihe therrnal treatrnentof TOP is perforrned in the presence of Water or steam. One focus of the methodaccording to the present invention is to decrease the viscosity of the TOP fractionproduced and to further simplify purification from salts and other impurities and tofacilitate blending With lignin.

The TOP may be recovered from any position in a crude tall oil fractionationplant or from a plant treating crude tall for the manufacturing of crude tall diesel. Priorto the use as blending stock for lignin the TOP is purified in one or more steps.Purif1cation of TOP is specifically targeting ash removal and is suitably perforrned byacid ref1ning With an acid such as sulfuric acid, f1ltration, solvent ref1ning and/ordistillation. The ash of the TOP content is loWered to a level below about 0.1 % morepreferably to an ash content beloW about 0.01 %.

The second component of the bio oil mixture of the present invention is purelignin. While it is of great importance to use a pure lignin, the method of purif1cationand processes upstream lignin purification may vary to a great extent. US 2016/0137680A1 discloses a method to obtain, fractionate, and purify lignin. The method Wassubsequently also disclosed in Chem. Commun., 2015, 51, 12855. The methodcomprises one or several separation steps Where biomass containing lignin is extractedand fractionated With an aqueous solvent With may comprise an organic acid. Themixture separates and one obtains one liquid phase Where high molecular Weight ligninis abundant and one phase Where the solvent is more abundant, but Which phase alsocomprises low molecular Weight lignin. The lignin phase can then be further treatedWith solvents to obtain a purif1ed lignin. Though metal content of the lignin is loWered,the method does not allow for nearly complete removal of sodium. Further, some ligninis lost, loWering the overall yield in the process.

In a process of repeated Washing of solid, dispersed lignin, With an acidicaqueous phase (cf. WO 2018/004447) a threshold is reached, as concluded in the 30experimental part herein below. It seems that entrapped sodium Will not be releasedeven if the Washing steps are repeated a number of times.

One particularly advantageous method for purif1cation of lignin upstream theTOP lignin mixing step of the present invention is by a solvent refining processspecif1cally targeting ash removal and in particular loWering the sodium content oflignin. The lignin may be lignin obtained from biomass, e. g. Wood, in a kraft pulping 5process. As an example, the feedstock may be black liquor comprising lignin. Given thehigh pH of black liquor due to the use of sodium hydroxide in the kraft process, at leastsome of the phenolic hydroxyl groups of the lignin dissolved in black liquor aretypically deprotonated With sodium acting as counter ion. At high pH, lignin is Watersoluble, Whereas lignin Will precipitate if the pH l0 is loWered as the phenolic hydroxylgroups Will become protonated, loWering the Water solubility of lignin.

A specifically advantageous solvent refining process for purifying lignin, saidlignin comprising metal cations such as sodium and calcium ions, comprises theconsecutive steps of: (a) providing lignin to be purified; (b) dissolving the lignin in an acidic, aqueous solvent, at a temperature of atleast 50 °C, such as at least 70 °C, 80 °C or 90 °C, to provide a liquid one-phase systemcomprising dissolved lignin; (c) triggering phase separation by diluting the one-phase system by addingWater, and/or by loWering the temperature, to provide a two-phase system, in Whichtwo-phase system the first phase is a lignin rich phase, and the second phase is a liquid,aqueous phase poor in lignin and comprising metal cations extracted from the lignin;and (d) separating the lignin rich phase from the tWo-phase system to recoverpurif1ed lignin.

It Was found that by employing a step in Which lignin is dissolved in a liquidone-phase system to subsequently be separated there form, a number of advantages areprovided.

By employing a method in Which lignin is dissolved in an acidic, aqueoussolvent, eff1ciently extracts sodium and other metal ions, Whereby metal cationseff1ciently are removed from the lignin, as they remain dissolved once the lignin isseparated.

Secondly, if employing many, repeated Washing steps, the overall yield of lignin may be loWered. In a process in Which a step of dissolving lignin in a liquid one phase system is included, the overall number of steps may be reduced, whereby improving theyield.

Thirdly the washing efficiency is improved by completely dissolving lignin inliquid one-phase system and subsequently triggering phase separation to form a two-phase system, compared to processes in the art (cf eg. US 2016/0137680) relying onliquid/ liquid two-phase system.

The inventors of the present invention have surprisingly found that a purif1edTOP with low ash content can be mixed with a pure lignin to form a substantiallyhomogenous bio oil mixture that can be used in various applications as a renewable fuelor feedstock for fine chemicals. The lignin can be mixed with TOP in pure powder formor dissolved in an organic solvent. The mixing efficiency, stability of and rheologicalproperties of the bio oil mixture can be improved by the addition of one or moreadditives to the lignin/T OP blending step or directly thereafter. Such additives arestandard surfactants with a selected hydrophilic lipophilic balance, preferably ethyleneoxide adducts, an anionic surfactant, cat ionic surfactants, zwitter ionic surfactantsmodified polyesters or polyelectrolytes. Also, water can be added to the mixture in lowamounts where 10 % of lignin weight has been shown to give improved mixingproperties of lignin in organic solution. The amount of water is preferably kept as lowas possible in a range from 1 % to 15 % of the lignin content. Other additives such ascarboxymethylcellulose and/or guar gums may also be used to improve mixing orrheological properties of the TOP lignin bio fuel mixture. Also, solvents may be addedto the biofuel mixture prior or during mixing, such solvents including green solventssuch as methanol, ethanol, turpentine, desalted low acid value crude tall oil (for exampletall oils with acid value below about 140 mg KOH/g) acetone or fossil blend stocks suchas light cycle oil or vacuum gas oil (VGO). Additives are added in an amount fromabout 0.1 % to 10 % and solvents may be added in any rage from 1 to about 60 %. Theproportion between lignin and TOP may also be varied within a broad range from 10 %lignin up to 90 % lignin (relative to TOP in the biofuel mixture). The mixing of thecomponents can be performed both in batch mixing reactors semi batch reactors orcontinuous reactors such as CSTRs or tubular reactors with static mixers orcombinations of reactors designs. The temperature during mixing should be kept high inorder to facilitate for the proper mixing of lignin, additive and TOP into a homogeneousmixture. The temperature in the mixing reactor(s) should be higher than 100 °C andpreferably higher than 130 °C.

Exemplarv embodimentsAccording to exemplary embodiments, the invention relates to: I. A low ash content biofuel mixture comprising tall oil pitch and lignin andoptional additives, said biofuel mixture possible to produce by a method characterizedby the following steps: - providing a stream of TOP; - providing a stream of organosolv lignin, hydrolytic lignin or purif1ed kraftlignin said lignin having an ash content below about 0.1 % preferably below about 0,01%; - mixing low ash lignin and TOP in a reactor, preferably mixing low ash lignindissolved in an organic solvent and a surfactant and TOP in a reactor followed byevaporation of the organic solvent upon heating; and - discharging a pumpable and substantially homogeneous low ash biofuelmixture comprising TOP and lignin from the reactor or more preferred discharging apumpable and substantially homogeneous slurry with lignin dispersed on a molecular level stabilized with a surfactant from the reactor.

II. Biofuel mixture in accordance with embodiment I, wherein the TOP has beenpurified by one of acid refming with an acid and subsequent removal of the acid phasefrom TOP, fine mesh f1ltration, centrifugation, solvent refming and distillation in orderto remove ash from the TOP to a level below about 0,1 % by weight preferably to alevel below about 0,01 % by weight.

III. Biofuel mixture in accordance with embodimentI and II, wherein the ligninhas been purif1ed by one of acid refming with an acid, solvent extraction or solventdissolution to remove ash from the lignin to a level below about 0,1 % by weight preferably to a level below about 0,01 % by weight.

IV. Biofuel mixture in accordance with any of the prior embodiments, whereinone or more additives are added to be present in the bio fuel mixture, such additive being a surfactant and/or a polyelectrolyte.

V. Biofuel mixture in accordance with any of the prior embodiments, wherein anadditive present in the biooil product mixture is ethanol, methanol, vacuum gas oil, acetone or low acid value tall oil.

VI. A method comprising using the biofuel mixture according to any of embodiments I-V as a renewable feedstock in petroleum refmeries, as a biofuel for power and/or heat generation, as a fuel for liniekilns or kilns for iron ore processing or as a feedstock for fine cheniicals or carbon fiber manufacturing.

Claims (10)

1. A method for producing a low ash content biofiael mixture comprising talloil pitch (TOP), lignin, and optional additives, said method being characterized by thefollowing steps: - providing a stream of TOP; - therrnally treating the stream ofTOP in the presence, of flwfater of steam and purifying the stream of TOP to provide purified TOP with an ash content below 0.1 %and decreased viscosity; - providing a stream of organosolv lignin, hydrolytic lignin, or purified kraftlignin said lignin having an ash content below 0.1 %, wherein the lignin has beenpurified by one of acid ref1ning with an acid, solvent extraction, or solvent dissolutionto remove ash from the lignin to a level below 0.1 %; - mixing the purified lignin and the purified TOP with decreased viscosity in areactor; the proportion between lignin and TOP being from 10 % lignin up to 90 %lignin relative to TOP; and - discharging a pumpable and homogeneous low ash biofuel mixture comprising TOP and lignin from the reactor.

2. The method in accordance with claim 1, wherein the TOP has been purifiedby one of acid refining with an acid and subsequent removal of the acid phase fromTOP, fine mesh f1ltration, centrifugation, solvent refining and distillation in order toremove ash from the TOP to a level below 0.1 % by weight, preferably to a level below0.01 % by weight; Éffr :'11 r iz, ti: 'TfÅIPP i; tl:ef,znftšll *rxat 'E in ptgeçaince of“;'~1te,

3. The method in accordance with claim 1 and 2, wherein the lignin has beenpurified by one of acid ref1ning with an acid, solvent extraction or solvent dissolution to remove ash from the lignin to a level below 0.01 % by weight.

4. The method in accordance with any of the prior claims, wherein one or moreadditives are added to be present in the biofuel mixture, such additive being a surfactant and/or a polyelectrolyte; and/or wherein water is added to the biofuel mixture.

5. The method in accordance with any of the prior claims, wherein a solVentpresent in the biofuel mixture is methanol, ethanol, turpentine, desalted low acid Valuecrude tall oil, acetone, or fossil blend stocks; preferably the solVent being ethanol, methanol, Vacuum gas oil, acetone, or low acid Value tall oil.

6. The method in accordance with any of the prior claims, wherein the purif1edlignin is dissolVed in an organic solVent before being mixed with the purif1ed TOP and asurfactant, the mixing optionally being followed by eVaporation of the organic solVent upon heating.

7. The method in accordance with any of the prior claims, wherein the step ofdischarging a pumpable and homogeneous low ash biofuel mixture comprising TOP andlignin from the reactor comprises discharging the pumpable and homogeneous low ashbiofuel mixture in the forrn of a slurry with lignin dispersed on a molecular leVel stabilized by a surfactant.

8. The method in accordance with any of the prior claims, wherein the methodfurther comprises a step of separating fatty acids, and/or rosin acids, and/orunsaponifiables, and/or their deriVatiVes present in the TOP and having an averagemolecular weight below 350 g/mol from the TOP by fractionation, before mixing theresidue TOP with the purif1ed lignin, using the residue TOP as blending stock for the lignin.

9. Use of the biofuel mixture pfgçiuggçgiaccording to any of claims 1-8 as arenewable feedstock in petroleum refineries, as a biofuel for power and/or heatgeneration, as a fuel for limekilns or kilns for iron ore processing, or as a feedstock for fine chemicals or carbon fiber manufacturing.

10. The use according to clairris 9, Wherein the biofuel rnixture is used as a fuel for a lirnekiln or a kiln for iron ore processing.