Quality and consistency drive Stephenville’s programs
By Pulp & Paper Canada
By Pulp & Paper Canada
Its history is chequered, the recent past has been a challenge with low newsprint prices but it seems there is a solid future for Stephenville. Built in the late 1960s as an ill-fated linerboard ventu…
Its history is chequered, the recent past has been a challenge with low newsprint prices but it seems there is a solid future for Stephenville. Built in the late 1960s as an ill-fated linerboard venture, the mill closed in 1977. During operation, linerboard production capacity was 350 000 tonnes per year (t/y). In 1979, Abitibi-Price (A-P) stepped in, buying the mill from the Government of Newfoundland. A-P installed a TMP plant and converted the machine to newsprint production.
Now, under the Abitibi-Consolidated name, the mill can produce 180 000 t/y of newsprint of varying basis weights from 40 to 48.8 g/m2. Its markets are far-ranging with regular customers in Europe, South America and Japan (see sidebar).
Mill manger Gord Cole said the mill’s recent efforts have focused on costs. “In our case, to try to increase strength without using kraft.” Stephenville must use about 7 to 8% kraft pulp in its furnish for the 45-g newsprint for its customers in Japan (6000 t/y). The mill’s total kraft use is less than 1%, most of which is purchased semi-bleached.
The budgeted efficiency for the machine is 91.6%, a target which has been achieved at time in the past. Stephenville can produce at a rate of 2.5 manhours/t, based on 48.8-g newsprint.
Plans for capital projects include a $4.5 million upgrade of the TMP process with the addition of chip washing and slotted screens. After that, Cole said the mill wants to look at improvements in forming technology. Finally, the third item on his wish list is a look at new calendering technology.
The mill’s effluent treatment system consists of a primary clarifier followed by an activated settling basin. Environmental performance for 2000 has been excellent with no violations of federal regulations for BOD, suspended solids or toxicity.
The mill’s woodlands are ISO 14001 accredited. Most of the mill’s raw material comes in the form of roundwood — balsam, black spruce — from its own limits. Stephenville buys chips from Newfoundland and Quebec sawmills. The mill will also buy wood from Nova Scotia and Prince Edward Island.
Balsam accounts for 60% of the mill’s volume, black spruce the rest, although very small amounts of white spruce are purchased from PEI. The black spruce is used for its strength properties; the balsam imparts the required optical properties.
The woodroom is a Rauma-Repola design, which is essentially unchanged from the linerboard operation, but operating at only 50% of its capacity. Chips from the woodroom are segregated by species and mixed according to manufacturing specifications.
Stephenville’s TMP process is a standard one, according to technical director Brad Pelley. There are four Bauer refining lines with four primary, four secondary and two rejects refiners. The mill can run three of the four mainline refiners at a time because of its power purchasing agreement with Newfoundland Hydro. (The mill does not produce any of its own electricity. Its power boiler burns Bunker C oil, bark and sludge to produce steam for the paper machine dryer and vacuum turbines.) At the current machine speed of 1080 m/min, Pelley said that when the mill is making newsprint heavier than 45 g, the TMP plant sometimes “struggles” to keep up with pulp production.
After mainline and rejects refining, there is latency removal, screening and cleaning, stock thickening and, finally, pulp storage (200 bdt at 5% consistency). The mill bleaches with sodium hydrosulphite, an average of 6 kg/t. Average brightness for all orders is 59%.
The paper machine is a hybrid. The headbox and former (Symformer) are Valmet. The press (tri-nip), dry end and winder (Super L) are Beloit. Maximum winder trim is 840 cm. Dryers are divided into four sections. The first two sections are unifelt runs and the third and fourth sections are conventional dryers with top and bottom felts. There is an automatic roll delivery system from the finishing department to the paper storage warehouse. The mill’s storage facility holds about one month’s production. Most of the newsprint goes out by ship. On average, a ship leaves Stephenville every 10 days and each can hold about 5000 t. A small percentage is trucked to Halifax, NS, and then shipped in oceangoing containers.
Stephenville has done some innovative work in the field of process control. A new Foxboro I/A system was installed in 1997. It is used to control the TMP and dry end of the paper machine. The next phase will see the system extended to the stock prep area (wet end).
In 1999, the mill entered a variability reduction program with Walsh Automation and Pacific Simulation. “The goal is to reduce variability in pulp and paper production,” Pelley explained. The contractual agreement deals with paper machine measurements: controlling porosity and maintaining a minimum tear figure. “From what we gather, this is the first time this type of work has been tied to the dry end of the machine,” Pelley added. “The goal is a more consistent product at the end of the day.” The process control is carried out by “soft sensors”, which are essentially software models, driven by process inputs and controlled based on the process results.
The mill has done its homework — paper machine efficiency is up and incremental speed-up is being achieved. The new process control equipment will ensure that high quality is maintained. Future projects, as noted, deal more with achieving high and consistent quality, not adding capacity.
ED. NOTE: Shortly after the presentation of the Safest Mill in Canada Shield, Class C, was made to Abitibi-Consolidated’s Stephenville, NF, mill, production manager Glenn MacDonald was killed in an accident at the mill. MacDonald was the co-chairman, representing management, of the mill’s Joint Occupational Health and Safety Committee. In an interview with Pulp & Paper Canada after the presentation, Mr. MacDonald and two other members of the committee spoke at length and eloquently about the mill’s safety programs and the workforce’s commitment to them. Having no accidents does not automatically mean a particular mill is a safe place to work. Just as a mill that does suffer an accident, even a fatality, should not automatically be condemned as an unsafe or dangerous place to work. As MacDonald and his fellow members of the committee pointed out, you can never “slack off” or let your guard down. “It’s a constant battle to maintain awareness.” All we can say, without meaning to sound trite, is to remember the inherent hazards in a mill and to be careful.
Stephenville newsprint is read around the world
Here is a partial listing of Stephenville’s customers. From England, The Times, Yorkshire Post and The Sun; from Italy, Corriere dello Sport; La Stampa, La Repubblica, Corriere della Sera and Il Mattino; from France, Derniere Nouvelle d’Alsace and Est Republicain; from Costa Rica, La Nacion; from Columbia, La Republica, El Tiempo, El Pais and El Columbiano; from Germany, Bild; from the Netherlands, De Telegraff; and from Japan, Asahi Shimbun (second largest newspaper in Japan) and Sankei Shimbun.