LOW CONSISTENCY REFINING OF MIXTURES OF SOFTWOOD & HARDWOOD

(ABSTRACT) The effect of refining energy on the measured properties of pulp and paper was investigated based on different ratios of softwood and hardwood chemical pulps in corefined blends. A mix of 70-80% lodgepole pine, 20-30% white spruce and 5% sub alpine fir was used as softwood and the eucalyptus as hardwood. The mixtures studied were 0/100, 25/75, 50/50, 75/25 and 100/0 hardwood/softwood at 3.5 % consistency. In the experiment studied here mixtures of hardwood and softwood bleached pulps were refined in a single disk refiner. The plate used had a BEL of 2.74 km/rev and the refiner speed was 1200 RPM. Gap size between plates was measured using a sensor connected to a LabVIEW interface. The different refining energy values were created by changing the gap size between plates at constant flow rate. The refining flow rate was 200 l/m. Refining hardwood and softwood together enhanced the paper properties such as tensile, burst strength, paper density and drainability, but reduced the tear strength, sheet thickness and light scattering coefficient. In order to significantly reduce the refining power, the ratio of hardwood must be 50% at least. We expect that the energy was put into the softwood pulp and resulted in a higher specific refining energy in the softwood fraction. No-load power did not vary with the % hardwood content. Fibre length weighted was reduced after refining due to fibre cutting and fines generation. (Conclusions) This research was carried out to determine the effects of mixing softwood and hardwood in low consistency refining for the purpose of making fine paper. The results can be summarized as below: 1. Decreasing softwood content in the mixture makes the pulp quality similar to hardwood quality. 2. As expected, refining hardwood and softwood together improved tensile and burst strength, increased paper density and improved drainability by decreasing the freeness. Refining also reduced tear strength, sheet thickness and light scattering coefficient. 3. As softwood content increased, the refiner was able to reach higher peak power and specific energy. With 100% and 75% softwood, we could reach 80 ±1 kW, with 25% we could reach 46.74 kW, while almost no power could be obtained with 100% HW. 4. The best tensile performance was obtained with 100% softwood pulps and 25% softwood pulps. We expect that the energy was put into the softwood pulp and resulted in a higher specific refining energy in the softwood fraction. 5. No-load power did not vary with % hardwood content. 6. The higher the hardwood content, the smaller the critical gap was. 7. Fibre length weighted was reduced after refining due to fibre cutting and fines generation. In 100% softwood, the fibres were 2.25 mm – 4.15 mm long. This initial length was reduced by 14.31%, while fines in the range of 0.2 mm – 0.4 mm long increased almost 39.53%. 8. The refiner plate with a BEL of 2.74 km/rev (bar width 1.6 mm) gave a better refining response to fibres with length > 1.6 mm. For that reason it is better for fibres with length > 1.6 mm to be refined with plate > 2.74 km/rev. Dimas DP Nugroho (August 2012)

Pakai Blackberry di Vancouver Canada

Saya sudah kecanduan dengan blackberry sehingga walaupun saya tinggal didaerah yang penuh dengan sinyal wifi tetap saja saya rela untuk menyisihkan beberapa dollar CAD untuk mengaktifkan layanan blackberry :D. Sama halnya seperti di negara kita Indonesia, banyak operator seluler yang ditawarkan dinegara ini. Kalau ditanya mana yang lebih bagus agaknya susah untuk menjawab. Semua punya kelebihan dan kekurangan masih masing. Jangan terburu-buru untuk memutuskan mau memakai operator yang mana. kunjungi saja setiap konter operator, disitu kita bebas mendapatkan semua informasi yang kita mau. kalau sudah yakin dengan satu operator baru silahkan anda mengambil keputusan. Pada saat tinggal di Vancouver Canada saya menggunakan operator FIDO (www.fido.ca). Pilihan paket bisa dilihat disini http://www.fido.ca/web/content/webads/plans_unlimited?cm_sp=Consumer-_-Q2_unlimitedplans_campaignpage_no_month_free_EN-_-Homepage_Hero_slot3 Untuk dapat mengaktifkan layanan blackberry, pada saat itu saya memilih sejenis paket pasca bayar dimana saya harus membayar 35 dollar CAD/month. Paket yang saya gunakan ini salah satu pake unlimited. Tapi bukan unlimited paket BB yang kita tau pada umum nya. Unlimited disini maksudnya adalah unlimitted call. Jadi di Canada ini yang saya tau, lebih popular paket dimana ada fasilitas unlimitted call. Fasilitas yang saya dapatkan kan dari membayar 35$ CAD/mont ini adalah Unlimitted Incoming local calls, Outgoing local calls, Text messages dan International text messages. Local disini maksudnya adalah se area Vancuver, tapi untuk text messages nya International. Jadi bisa sms ke seluruh dunia dengan 'free'. dan yang pasti fasilitas Blackberry messanger tentunya ^^. Tapi BBM paket nya disini tidak unlimitted. hanya bisa BBM saja. kalau misalnya anda ingin menggunakan fasilita BBM dan email, anda dikenakan tambahan biaya 10$ CAD/month (http://www.fido.ca/web/content/messaging/blackberry). kalau saya sih asal BBM nya sudah hidup itu sudah lebih dari cukup. kalau download download file mah bisa di laptop dengan menggunakan fasilitas free wifi di zona free wifi. Oh iya, kalau BB nya sedang connect dengan WIFI, facebook, twitter dan foursqure bisa aktif juga. tapi kalau terdisconnect dengan wifi nya otomatis hanya bisa BBM saja. Note: jangan lupa selalu menambahkan 12% di perhitungan anda untuk membayar pajak setiap apapun transaksi yang kmu lakukan di negara ini. Semoga berguna :)