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RONNSKAR: Double Up, Without Downtime.

A seasoned European smelter embraces castoffs of the high-tech world...and expands

Paraphrasing a catch-phrase of 19th century gold rushers, "there's gold in them thar hills" cellular phones. Some 220 glint to be exact.

E&MJ recently met with management at Sweden-based, Boliden's Ronnskar smelter--the nation's only copper/lead producer--in Skelleftehama. From its commissioning in 1930, the 10K-mt/yr (copper) smelter was originally sited on the Gulf of Bothnia with an eye to minimizing environmental impacts-[SO.sub.2] effects on a prime economic sector of the period, the inland forests. Emissions of 175K mt/yr in the 1930s have dropped to a current level of 3.5K mt/yr. And what then might have been something of an afterthought, Ronnskar' s tidewater location, is today a double blessing-for its shipping costs and competitiveness in the world.

While the recycling business is certainly growing, Ronnskar capacity was expanded, from 140K mt/yr cathode to 240K mt/yr [*], to meet market opportunities--supplied by both conventional primary (in-house and purchased from the Escondida, Collahuasi, Los Pelambres, and Bato Hijau mines) as well as secondary feeds. [**] A key post-expansion company goal was to maintain the smelter's status as one of the world's cleanest.

A traditional approach would be to engage a major EPCD firm to scope Out, design, and construct the facilities. Boliden took a different approach. Many readers can relate to the old adage: if you want something done it yourself. That is exactly what management decided to do. Rather than endure likely glitches, "gotchas" (in change orders and costs), and finger pointing, it created a pragmatic expansion of management. An experienced project manager, Osten Isaksson, was brought aboard. He, in turn, oversaw eight key in-house production-managers for each component of the expansion. This organizational structure was used to assure a smooth transition. Low-level problems were resolved by a high-level steering committee to minimize managers' conflicts. Making harmonious and effective management critical was the additional challenge of maintaining smelter output with no shutdowns. For design coordination it was decided to use Boliden Contech, Boliden's in-house engineering company. Some 160 contractor com panies, with 1,500 workers (780 peak onsite) racking up 1.8M man-hours, were contracted by Ronnskar.


Some prologue is in order: Boliden had concluded that cost-cutting was needed, which included reducing overheads by combining the Stockholm and Toronto offices. From a staffing of 2,600 in the mid-80s, Ronnskar's employment has dropped to 850 today (40 of whom are directly attributable to the 70% capacity expansion). However, physical cost cutting only brought Ronnskar part way to the cost competitiveness needed. Greater efficiency was needed.

Management reviewed competitive history with E&MJ, which was integral to the decision-making:

So the biggest benefit was seen coming from fundamental operating cost efficiencies integral to ever-increasing capacity and the resulting economies of scale. Competitive analysis and strategic planning dated from 1995 to 1997. Thereafter, the project was on a fast track: July 1, 1998, the board decision for expansion was taken; and by August 21, construction began on the 24-mo program, costing about $245M.


Integral to the decision, key expansion objectives included:

* Proven technology with a short learning curve;

* Proven low-emissions for air and water;

* New smelting process amenable to the existing flowsheet;

* New smelting process has to have a wide production range to minimize future investment; and

* New smelting process must be energy efficient.

Major elements of the expansion included:

* Harbor improvement, 300 m with a draft of 13.5 m--allowing simultaneous docking of two 50K-dwt-capacity ships raising capacity from 1.6M mt/yr to 2.5M mt (with land transport capacity to and from the smelter rising a further 250K mt);

* Quay-side 1,000-mt/hr covered conveyors, replaced trucks, and reduced fugitive dust emissions;

* New: blending storage; dryers; Outokumpu flash furnace; converters; overhead cranes; anode furnace; 100-mt/hr anode caster; oxygen plant; and purification plants for electrolyte and process gas;

* Acid plant expansion; and

* 120-m expansion of tank house (now 400 m total) with: Mt. Isa-technology stainless starting-sheets, stripping machines, new rectifiers, new circulation systems, etc.

Besides the challenges of expanding an active plant, covering 1 x 1.5 km, it had considerable "baggage." Over 90 buildings, spanning Ronnskar's 70-yr existence, were demolished during the program.


The additional smelting is accomplished with a system comprising: two parallel, steam-operated concentrate drying lines and dry concentrate pneumatically conveyed to the loss-in-weight system (for even flow to the concentrate burner); flash smelting furnace; waste-heat boiler; electrostatic precipitator; gas quenching; and the Boliden Contech Hg removal system--developed jointly with Norzink--to assure high-quality acid product.

The flash smelting furnace incorporates a semi-closed cooling system, the latest design for concentrate burners, cooling around the tap holes, improved slag-launder design, and a new roof tension system. Foundation construction commenced June 1999 and startup occurred August 2000.

Improved classic boiler-design was also incorporated, such as beffel, common roof-level, integrated conveyor arrangement, and no-expansion ballow-in-boiler body.

In addition, the electrostatic precipitator has switched integrated rectifiers and externally-mounted hopper hammers.


Matte will continue to be converted using the Peirce Smith process. Capacity improvement was achieved by larger converters, increased blast rate, [O.sub.2] enrichment, and a higher matte grade.

The converter aisle was built around the existing aisle allowing for two new cranes and new gas-collection hoods; it is perhaps one of the best examples of the no-shutdown expansion. The new aisle is 8 m wider and 8 m higher than the old one. After the two new 100-mt capacity cranes were installed, they lifted off the roof and cranes of the old aisle. A new manipulator feeds scrap to the converter without tilting it down. And the converter in action was the cleanest that the writer has seen.

The larger converters, with 60 tuyeres, handle 250 mt/batch with a blast rate of 700 N[m.sup.3]/min and on-demand [O.sup.2] enrichment. New primary- and secondary-hoods were also installed. And scrap can be charged during blowing (one converter at a time). A new bag-house filter cleans all ventilation gases flowing from the aisle's secondary hood, converter aisle, and from the flash smelter building.


The new, 100 mt/hr casting shop incorporates one new 350-mt furnace and Outokumpu twin-wheel caster. Liquid ammonia is employed for oxygen removal from the blister.


The tank house was expanded in both directions. The number of sections was increased to 32 each consisting of 28 cells. The resulting symmetrical refinery has all electrode handling in its middle. Current density rose from 295 A/[m.sup.2] to 330 A/[m.sup.2]. New rectifiers, a new bus-bar system, and electrolyte circulation systems were installed. Electrolyte purification capacity was boosted with a new copper sulphate evaporator in parallel with the preexisting decopperization plant and prior to the nickel sulphate evaporator. And E&MJ saw and walked upright through the well lighted, clean "basement" of the tank house.


Productivity has shifted remarkably from 50 mt/employee in 1980, to 240 mt in 1999, and to an estimated 360 mt/employee in 2000. And, echoing the axiom that a safe operation is a productive one is the shift from a historic accident rate of 22/ 1M hr, dropping to 1 1.5/1M hr now.


E&MJ appreciates the hospitality and candor of Johan Wiklund, general manager; and Theo Lehner, metallurgical supervisor.

(*.) Post-expansion output: 240K mt Cu, 40K mt Pb, 40K mt Zn, 450K kg Ag, 14K kg Au, 500K mt H2S04, and 60K mt [SO.sub.2] (liquid)--plus Se, Cu-sulphate, Cu-telluride, and crude Ni-sulphate.

(**.) Recycling feedstock includes an estimated 25% of the world's printed Circuit boards. Of Ronnskar's output, recycling-sourced feed yields about: 20% of the copper; 50% of the gold coming from "old gold," plus 31% from electronic scrap: and 90% of the zinc. Boliden runs five weekly trains shipping copper cathodes from Ronnskar to the south of Sweden, and brings electronic scrap from Europe to the smelter as return freight.
                         Copper Raw Materials 2000
Other recycled materials    14%
Electronic scrap             2%
Aitik concentrate           27%
Other in-house concentrates  5%
External concentrates       52%
Year    Output      % of Smelters
     (k mt/yr Cu) w/Output Specified
1950      35              40
1974      65              60
1986     100              50
1995     100              70
                      Expansion bottom line, on time,
                             and under budget
Investment     $2,740/mt capacity
Operating Cost 8[cent]/1b, incremental
Playback       6.4 yr
IRR (BFIT)     15.1%
IRR (AFIT)     32.5%
Next step: 300K mt/yr (date unspecified) copper.
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Title Annotation:Ronnskar smelter
Author:Phelps, Richard W.
Publication:E&MJ - Engineering & Mining Journal
Article Type:Statistical Data Included
Geographic Code:4EUSW
Date:Feb 1, 2001
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