CEE Oct-Dec 2002

atmosphere have peaked or are on the dec line. llowcver. the report from that Nairobi-based UNEP and the \.Vorld M eteo rolo g ical Organi zation says the ozone layer will remain vu lnerable during the next decade o r so . The report comes from a panel that has rev iewed the status of the ozone layer once every four years since an internation al treat y on ozone– depleting substances, known as the Montreal ProtocoL came into e1Tect in 1987. I ndustrialized countries have phased out most substances blamed for depleting the ozone layer. such as chloronuorocarbons, once \\ idel y used in ae rosol propellants. airconditi oncrs, and refrigerators. ( ·ourtesy: TER! Newswire 16-30Sep.2002. f>l5 & 21 t.,"-muil: outreuc:h!a teri.res.in II "eb. II'WW. teriin.orx WASTE TO WEALTH COINCINERATION ON CEMENT KILN AN INTEGRATED APPROACH BY LIFE CYCLE ANALYSIS (LCA) The use of alternative materials in the clinker burning process considerably reduces the impact on the envi ronment. Int egrated assessments show that this permits to reduce energy consumption and thus COl emission. In addition to th at, the quan tity of was te is diminished signi ficantly. Life cycle analyses arc used to investi ga te was te material s v<~ lori sccl /el iminatcd in ditTercnt processes. A lithe constituent steps are <1nalysed and the environmentally relevant input and output v<~ riablcs arc determined. First integrated assessments arc avai lable for the usc of pl<lstics and \\aste Oil. It becomes evident from the use, I kg of plastics in a cement plant r educes the emi ss ions of green house gases, such as CO, by about I kg ( in CO, equiva l e~1ts). This value includes the substitution of coal. Pure waste incineration emits an additional 0.87 kg of CO, . Like singIe-materia I combu-stion, methods focussed on materi al recover y and utili sa tion in bl as tfurnaces on ly marginally reduce C0 2 emission s. Mono– combustion (Cr8) outperforms dedicated waste incinerati on, reducing co1 emi ssions by 0.29 kg C0 2 per kg of plastics incinerated. The example of COl emi ss ions underscores that plastics utilisation in cement plants is clearly superi or to the other methods. Waste oi l i s either utili se d energeticall y in cement works, or recycled into lubricants in waste oil refineries. Integrated assessment take s int o account th at it thu s substitutes for coal as a fuel in cement works. Recycled waste oil , on the othe r hand. must compl y with the spcci lications applicable for high-grade engine oil. Use of waste oil as an energy med ium in cement plants i n comparison to the reprocessi ng of waste oil into base oil for lubricant production. This balance takes the entire previous processes (t ran sport, coal mining . oil exploration) int o account, thus crea ting the basis Cor integrated assessment. From the examples of energy consumption and greenhouse gas emi ss i o n, it becomes evident that waste oi l use in cement plant s c l ear ly outperforms reprocessing. Courtesy : Indian Cement Re1·iew. A11g. 2002. Pp 11- 13, Fox: 0091-22- 20-2102 Eniai f: meherlci)bomJ.vsnl. net.in.l \l'{:ui/Jeraptiblication@vs!d. IIL' f 60 INFLUENCE OF MARBLE POWDER ON MICROSTRUCTURE ANO HYDRATION OF CEMENTS f>elin Turker. Ba/Jadir Erdogan Turkiye Cimento J\1/ustahsi//cn Birligi, Korlwn Erdogdu Marble wastes from quarries and ma rble fac to ri es provide a sustainabl e source f o r cement fac tor ies to produce portland– l imestone cements. Thi s pape r eva l uates the usage of marb le was tes as a I imestone-acld i t ive source and prov ide practical data for understandi ng the behaviour of marb le in cement. In the st udy, portland-limestone cements with 5 to 30% marbl e and 3600 ± 75 cm 2 / g Blaine fineness were produced by intergrinding. The hardened cement pastes were investigated by SEM at 2 and 2 8 days. Compressive strength, setting times and normal consis tence or the cements we re also dcte rmined. Results yielded that in cements with marble. reaction products tend to accumul ate arou nd the calcite crysta ls and Cll morpho logy is completely different from that or portland cemen t. St re ngth i s decreased wi th increasing marble amount in cement at all the ages tested, and the strength loss is lower at earl y ages. Increas ing marble amount in cement increases setti ng times moderately. Blended cements ha ve been produced to an increasing extent in cement industr y due to some techni cal. economi c and environmemal reasons. In addition to the conventi onal int ergrouncl add iti ves. i .e. natural pozzolana, slag . etc, recent l y u s <~ ge of limestone has also become popular in cement industry especially wi th the advent of new European Standards.