A penetrative addictive for water infusion in coal seams

Journal of University of Science and Technology BeijingMineralVolune 10, Number 2, April 2003, Page 16A penetrative addictive for water infusion in coal seamsLonszhe Jin, Wen Ni, Qingsong Wang, and Wei WeiTD8 ACivil und Enironmental Enineering Scool, Univesity of Science and Tchnologoy Beijing. Bejing 100 China(Receved 2002-05-31)Abstract: The manufacturing process. charateristics. and application results of a rod-lie penetrative additive (the penetrative rod)were discussed. The components and functions of the penetrative rod were studied carefully. A large number of otbogonal combinedtests were crried out and over 100 sample molds were made. Utimately the components were decided after careful selection amongthese molds, mainly including hygroscopic major components and auxiliary material. The results of on-site practical applicationshow that such an addictive can increase the water penetrative ability efectively and has a remarkable effect on preventing dust pro-ducti )n during coal scam excavation. The penetrating radius, the infusing velocity and the dust-preventive effect were systeaticallystudicd.Key words: coal seam water infusion; penetrative; penetrative rod: additive1 I.troductionproduce a high efficient penetrative addictive with arod-like shape. To enable the technology to be com-The earliest study of using additive in infusion wa-mercially practical in the large-scale application. de-ter to prevent dust was made by some German re-tailed researches have been done to simplify the op-sear:hers. A test of increasing glutinosity by addingerational progress for use.matcrial, such as Retatin 819, Retatin FS62, etc.. intothe infusion water was carried out successfully in2 Composition of the penetrative rodRuh- Mine of German in 1968 [1]. The results weregood and the effects were evident. However, the2.1 Components and functionscommercial application was not achieved due to itsBesides determining reasonable infusion parame-inconvenient process of adding into the water and itsters, decreasing the water surface tension and pre-over sensitivity to the characteristics of coal seams.venting it from being evaporated are considered asSome further researches were carried out in Poland [2],two primary ways to further increase the efficiency ofGernan [川Former Soviet Union [3] and France [4].dust prevention when the technology of coal seamSome good results were also reported. In the 1990s thewater infusion is used [5].technology of dust prevention by glutinosity wasResearches and analyses have conclusively estab-quickly developed. Good results of dust preventionlished that appending hygroscopic material can pre-wer: achieved by adding glutinosity into the infusionwater during coal seam excavation in Germany, USA,vent infusion water from being evaporated, while ad-ding surfactant material can decrease the water surfaceFrance and other countries.tension. A large number of orthogonal combined testsThe studies of adding some surfaclants into the in-between more than 40 kinds of organic monomers andfusion water were carried out in some research insti-hygroscopic material were carried out. Over 100 sam-tute: of China in 1990's. Some industrial experimentsple molds were made. Ultimately the componentswer: done in Datun Mine， Yinggangling Mine,were decided after careful selection among theseZhenizhou Mine, etc. Some desirable results were re-molds, mainly including hygroscopic major compo-port:d [3].nents and functionary surfactant combined substanceEven though good experimental results of dust pre-(als中国煤化工/hich can lower thevention were achieved, many of these techniqueswat iYhCNMH(_mitigating corrosiondidn't reach a commercial level of application due tond..site application, thetheir complicated process of use and inconvenient op-additive was made into solid rod-like material aseration. To overcome these shortages, this study is toshown in figure 1, here shorly named as "penetrativeCorn:sponding author: Longzhe jin, E-ml: logheji001@ 163.com17L.z. Jin et al, A penetraive adictive for water infusion in coal seamsrod". It can slow deliquescence, keep on caking dust,2.2 Selection of major componentsdecrease !he water surface tension and prevent infu-In view of the function, the hygroscopic (prevent-sion water from being evaporated.ing evaporation) character should be firstly consideredwhen selecting major components. The hygroscopicmaterials are generally divided into two types: ad-sorptive hygroscopic material and chemical hygro-scopic material. The former mainly inctudes silica ge(mSiO2. nH2O)，molecular sieve (Me,/ [(AI02)45 mm(SiO2)J1 . mH2O), alumina gel (Al2O3), activated car-500 mrbon, bone glue, floridin (Al2O3;" 4SiO2 : nH2O), etc.while the latter mainly includes calcium chloride(CaCl2 . nH2O), magnesium chloride (MgCl2 . nH2O),Figure 1 penerutive rod sketch.calcium oxide (CaO), phosphorus pentoxide (P2O3),The ccmponents and functions of the penetrativeglycerin (C;H(OH)3). caprolactam (NH(CH)OH)，rod are pr :sented in fgure 2.and diglycol (CH2OHCH2OCH2OH) [6].Penetraive rod formulation'sparls & functionsAuxiliary materialMajor components('alcium chloride &SurfactantCorusionDispersantmagnesium chlorideThickenerinhibitorC AdvantagesDisadvantagesFunction ) ( FunctionFunctionFunction)StronpC austicityahsorpivabsorptivesurfaceDecrease majorcompunenis'SmallIncrease' corrosion rateDisperse auxiliaryInexpensivevisciditymaterial equalityFigure 2 The parts and functions of penetrative rod.According to the above materials' chemical affinityvantages, such as large surface tension of water solu-with wate. source, price and other factors, the authortion and others, can be remedied by adding auxiliarybelieves t1at calcium chloride and magnesium chlo-material.ride are more suitable for Chinese mining industry.2.3 Selection of the auxiliary materialBoth Ci lcium chloride and magnesium chloride notAs discussed above, the selection of the majoronly have good hygroscopic characteristic. but alsocan meet the application conditions of chemical pro-components is mainly based on the hygroscopic char-ductions under the mine. That is (a) they have no poi-acter (evaporation protection) of the penetrative rod.son. no bad smell. and no pollution to environment: (b)But the surface tension of inorganic salt solution isthey can easily be dissolved in any well water withlarger than that of pure water (72.75 mN/m at 20C inhigh solut ility; (c) they are never capable of buming.pure water, measured in laboratory). However, as acombined substanceof muli-function surfactants,explosion: and (d) they never erode metal obviously.auxiliary material plays important roles in decreasingAs 90% of the penetrative rod is the major compo-the surfac中国煤化工; solution. andnents, ther price directly influence the total cost ofenhancindispersing,penetrative: rod. Therefore the inexpensive calciumthickeninYHcNMHGselecingthechloride and magnesium chloride should have a brightsurfactant, which has good compatibility with calciumprospect cf commercial application. And their disad-chloride and magnesium chloride, is the key techniqueJ. Unir. Sci. TechnoL Beijing, Vol,I0, No.2, Apr 200318for wetting coal seam by using the penetrative rod aq-inorganic salt solution, but also we ought to solve theua mc re efectively.problem of compatibility between surfactant and inor-ganic salt solution in the course of selecting surfac-The: inorganic salts have lttle influence on nonionictant.surfac tant, sometimes they may even be dissolved inthick salt solution or base solution, and easy to sepa.Table 1 lists some surfactants' surface tension inrate ionic surfactant salt from solution. Therefore notpure aqucous solution and inorganic salt solution,only :;hould we consider its absorptive quantity fromwhich were tested in laboratory.Table 1 Surfactant adsorption in pure aqucous solution and inorganic salt solution (20C)Content of theSurface tension 1 (mN+m~' )Surfactantadded agentPure aqucous30% inorganic saltsmanufacturersolutionFally alcohol amide 7041.38.6365.21Beijing0.31.6535.55TianjinOrπ--I533.8636.05Dispersant calcium soap41.6536.75XingtaiPenetrative agent JFC29.7534.54Triton X- 10029.4332.32Hong KongSpan 6034.3676.87BeiingTrethanolamine oleale1.046.0775.62 .Detergent AN36.7848.59AlkyI quatermary ammonium sals3.040.3283.43Viclory oil-field;R- I32.7677.6131.2333.26Combined38.9741.0729.65As adding surfactant not only decreases the surfacetant need to be combined. The optimized compound-tension of inorganic salt solution, but also enhancesing was decided through orthogonal combined tests.the fi nctions of wetting, dispersing, thickening, andTable 2 lists the orthogonal combined test of the classmitigating corrosion, etc.. one more kinds of surfac-of fatty alcohol polyoxyethylene ether surfactant.Table 2 Fatty alcohol polyoxyethylene ether class surfactant combined tests lableTestCombined surfactantsInorganic salts solutionNo.CuuE__ CrEm_ C.En_ CieE. C1gEmsurface lension/ (mN-m~) soakage speed 1 (mg:s~ )45.930.87946.110.84147.680.96;131349.421.5858.641.77111I46.770.8651.730.741554.870.82552.330.631046.980.58.....Note: C- alkyl chain: E- -Epoxy ecthane; m- -the number of epoxy ethane adduct.The thermal compound craft is required during theof fattyv alcohol polvoxvethvlene ether surfactant.manufacturing the penetrative rod, thermal decompo-Ta中国煤化工actants have com-sition of the surfactant must be considered. ThereforpletelCNMH GSo only by adingthe decomposition under different temperatures wasPau uluicu swTallaut al ucultemperatures cantested. Table 3 shows the decomposition of four kindsremain the native chemical character. During the proc-19L.z. Jin etal, A penetrative addictive for water infusion in coal seamsess of pur fying. water was evaporated and the solu-terial. The P3 combined substance, made up of manytion became the crystal of pure inorganic sal. Fur-surfactans, can decrease the surface tension of allthermore the surfactant decomposed at low tempera-kinds of inorganic salt solutions in a great range, asture must be added in solvent spray way.well as play a part role in wetting, dispersing, thick-According to the experiments of orthogonal com-ening and mitigating corrosion, etc. P; is stable mate-bined and thermal decomposition, the P; shown in ta-rial at both low and high temperatures.ble 2 is selected as the penetraive rod's auxiliary ma-Table 3 The thermal decomposition characters of the surfactantsi/CPeregal 0Peregal OS 15Penetrative agent JFCDispersant calcium soap5(Begin dissolveNo dissolveDelaminateNo change8(Full dissolveBegin vaporize and bubble up100Begin bubble up No changeMore bubble up150More bble up Begin bubble upBegin bubble up More bubble up200Begin dssove Begin bubble down_2503 Properties of the penetrative rodand the penetrative rod solution points out that theamount of breathing power produced in breaking coalThe penetrative rod is the off-white and rod-likedecreases by 25% with the increasing water content ofcrystal configuration. According to the measurement,coal. But the decreasing trend will be ltte when theits basic characteristics are as follows: it tastes slightlywater content increases to 3.2%. The larger the watersalty, it hus no bad smell. the pH value is 6.9-7.3, thecontent, the bigger all kinds of equivalent diameter ofviscosity of the solution including 30% water (at 25C)the broken granule. Compared with pure water, theis 6.49 πPas, the melting point is over 650"C, thepenetrative rod solution can prevent the dust producedsolubility in water is 816 g/L. the dissolving heat isduring coal excavation effectively, and the breathing-9.8 kJ/mol, the amount of solid is from 68% t0 71%.power can fall by 35.3% on average [7].the corros ion rate to carbon steel at normal tempera-ture is below 0.2 mm per year. There is no thermal de-The applied experiments were carried out in Yao-composition phenomenon under normal temperatureqiao coalmine and Taoyuan coalmine. After addingand no harmful gas when it is heated. It can corrodethe penetrative rod in the coal seam infusion craft, theleather to some degree [5].wetting radius could reach 32 m while that of the gen-eral water infusion only reached I5 m. the water con-The absorbing moisture equilibrium is one of thetent could increase by 75.7% compared with the gen-most imp ortant characters of the penetrative rod. Re-eral method. According to the pertinent experiments,searches indicate that when the absorption speedadding 2% to 16% dosages of the penetrative rod cantrends tow/ard zero at cerlain humidity, both compara-decrease the evaporation by 20% -82% [8].tive absorption quantity and the solid content of thepenetrative rod tend to be constant. The mechanical4 Conclusionsmeasurenuent of the penetrative rod with differentconcentration shows that the surface tension of the(1) After adding the penetrative rod, the wetting ra-penetrative rod's solution can be reduced by 1.86-2.57dius and humidity increase obviously, and the preven-times, the viscosity can increase by 2.45-32.75 times,tion of being evaporated becomes effective.and the soakage velocity to coal dust reaches 0.19-(2) Using the same infusion parameters, the infu-2.57 mg/; while that to pure waler nearly reachingsion velocity after adding the penetrative rod can in-zero. The contrastive experiment of coal body nativecrease by 1.57 times. The new craft achieves the sameseepage indicates that adding the penetrative rod 10water can improve the effect of soaking coal body ob-result in short time, which can be got by using the tra-viously. the humidity of coal can increase by 15 times,ditional pure water craft in long time.the losing; water rate of coal can be reduced by 2.8(3)Co中国煤化工_usion craft. thetimes, and the losing waler velocity can decrease bydust procMHC N M H Gprocedure can7.7 times. The contrastive experiment of the influencereduce by U.3-J.4 wu.I，uc illuue of reductionon coal b ody which produce the dust from pure watercan reach 1%- 39%, and the decreasing rate of dust can20J. Univ. Sci. Technol. Beijing, Vol.10, No.2, Apr 2003increuse by 26.2% in working face, of which the tra-ingemosions and compositin [P]. the United Stales pat-ditiondl infusion and the adding the penetative rodcnt. patent number: 4594268.infusi on are respectively 54.4% and 80.6%.I51 L.Z. Jin. Tes of dust fall by adding the dust-adhcring barwhen coal seam water-infused (JI，J. Unin. Sci. Techmol.ReferencesBejing. 23<2001), No.1. p.1.[川1. G. Jin, Germuan coal seam waler infusion to control dust61] C.z Yu. Chemical Engincering Thesaurus {M], Chemistryd-vclopment trend川Coal Engineer. 5(1994). p.46.Industry Press. 1992.21 Siodek do awaleania zagrosen pylowrych IPI. the Polands17| K.T. Fang and C.x. Ma. Orhogonal and Smrical Tesnpitent. patent number:239007.Design [MI. Science Press, Beijing.2001.[3| L.G. Jin. The Research andAplicaion Sticking-dust(8| L.G. Jin and Z.G. Jiang. Sudy on phenomenon of waerT:chnique (DI. China Universityly of Mining and Technol-vaporization during infusing water into coal seam小ChinaOy. Beijing School. 1997.China Safery Science Joumal, 10(2000. No.3, p59.141 Method for the conrol dust using mehanlete cotain.中国煤化工MHCNMHG