Drives Enhance Energy Efficiency in Wastewater Aeration

Known as the “Land of 10,000 Lakes,” Minnesota takes its environment and its water resources seriously. That is why the city of Mayer, a town of about 1,800 in Carver County, Minn., was proud to have its wastewater treatment plant operator recognized by the Minnesota Rural Water Association (MRWA) for implementing innovative energy savings using variable frequency drives (VFDs).

The recipient of the award, Greg Kluver, had worked for Mayer in several capacities since 1990 and is currently the wastewater contract operator.

“During the last few years, municipal budgets have been under a lot of pressure,” he said. “In 2010, I proposed that Mayer invest in variable frequency drives to cut the cost of running the wastewater treatment plant’s biggest energy users, blower motors.”

The Plant’s Operation 
The treatment plant uses three blower motors to perform aeration, one of the most important functions of the wastewater treatment process. Blowers agitate the sewage and inject oxygen into the water so that microbes can remove contaminants. However, the amount of oxygen must be precise. Too little oxygen will prevent the microorganisms from breaking down the organic waste. Too much will cause the microbes to cannibalize themselves and die.

Kluver noted that Mayer’s water treatment plant was designed as an extended aeration activated sludge facility, which depends on maintaining the proper balance of microorganisms. In this plant design, the influent, incoming wastewater flows into a pretreatment building to remove physical material, such as grit and sand. Then primary treatment begins. Sediment is settled out, and phosphorus is detained by using an anaerobic and anoxic tank in which the bacteria, in the absence of oxygen and nitrates, accumulate phosphorus.

In the secondary treatment phase, the wastewater flows into two aeration basins, in which it is continuously agitated and injected with air. The added oxygen triggers the microorganisms’ aerobic digestion process, feeding on the organic matter and removing nitrogen and ammonia. As the microbes flourish in the oxygen and nutrient-rich liquid, they clump (flocculate) together to form a mass of organic solids, known as a biomass. This biomass is also called a mixed liquor.

The mixed liquor flows to a secondary clarifier (settling tank), in which the activated sludge settles out. A portion of the sludge is returned to the head of the aeration basins to maintain a high population of bacteria to break down the organic material and maintain a constant flow rate. The remaining sludge is pumped to a digester, where it is stored. It is then transferred by truck during the spring and fall to another facility for final treatment and disposal. The remaining clear liquor passes through bridge sand filters and ultraviolet disinfection before being discharged to the south fork of the Crow River.

The VFD brings the blower up to speed by ramping the voltage. The newly installed VFDs can also be programmed to receive a signal from the dissolved oxygen sensor and adjust the blower speed accordingly.

The Addition of the VFDs 
Together, the two concrete aeration basins can handle a combined volume of about 320,000 gallons per day. To supply enough oxygen into the wastewater, the blowers must deliver up to 650 cubic feet per minute of air.

“We have three 40-horsepower rotary blower motors configured in parallel,” said Kluver. “They are 60-hertz, positive-displacement root blowers. The blowers run one at a time for 24 hours per day, for a predetermined time period. Then we cycle on the next blower to equalize the run time between all three.

“This application requires constant torque (CT). In CT applications, torque is directly related to current. That means a VFD maintains CT by increasing the voltage in a linear manner as speed increases.”

The VFD slowly ramps the voltage to bring the blower up to speed. The newly added VFDs can be programmed to receive a signal from the dissolved oxygen (DO) sensor and adjust the blower speed accordingly.

“The great thing about a positive displacement blower, as soon as the rotor turns, it is pushing air into the process,” said Kluver. “This creates an almost perfect linear performance curve. The higher the voltage, the faster the rotor speed, and the greater the airflow. On the other hand, if we only need half the air, we can reduce the blower speed and the horsepower by 50 percent and cut the kilowatts in half.”

Kluver contacted an equipment supplier near St. Paul with a VFD specification, and the supplier recommended a VFD that was dedicated to water and wastewater applications. This allowed for simplified implementation. The VFD had many built-in features—including a cascade controller to radio frequency interface filter to input the choke to real-time clock.

On this plant’s basic positive-displacement blower project, the equipment supplier and Kluver took advantage of the built-in water/wastewater intelligence. They were able to input the DO value into the on-board, closed-loop control of the drive. The VFD display then showed the actual DO value, DO set point, motor speed and kilowatt consumption. As a result, an integrator was not needed, which helped with cost savings.

“Another cool feature is the VFD’s payback time,” added Kluver. “We entered the price of electricity, which is about seven cents per kilowatt hour, the equipment investment, and the load profile for the application. The VFD comes with software that continuously calculates the remaining payback time right on the display. It’s a great way to show how energy savings add up and when the investment is paid back.”

Kluver also appreciated that, when considering the implementation, a VFD was lent as a loaner.

“The supplier was really easy to work with. The loaner let us verify that the drive would work with our blowers and that we could get the energy efficiency we were hoping for,” said Kluver.

The drives are enclosed in National Electrical Manufacturers Association/Underwriters Laboratories (NEMA/UL) Type 1 cabinets in the blower room. No special ventilation was required or used. The VFD was able to handle high temperatures well. It is rated up to 50 C (122 F),

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Peel spreads out as Mallee Bull comes into focus

PEEL Mining has reached an agreement to purchase an exploration licence 20km north of its promising Mallee Bull copper project in New South Wales.

The news immediately followed a Peel presentation at the Resources & Energy Investment Symposium in Broken Hill, during which managing director Rob Tyson aimed for a Mallee Bull resource estimate by early next year.

The company identified the newly acquired Sandy Creek prospect as having a similar geology and structural environment to Mallee Bull, along with coincident magnetic and electromagnetic anomalies including a strong downhole electromagnetic anomaly of about 30 milliseconds time constant. 

Peel said strong geochemical anomalism had also been established at the licence, including high-grade polymetallic historic drilling results.

The deal arranged with private party Weddaria includes the issue of 1.2 million Peel shares with a value equal to $A775,000 and a 1.5% net smelter return royalty.

Yesterday, Tyson told delegates at the Broken Hill symposium that Peel had picked up about 3000sq.km surrounding Mallee Bull, which is part of the broader Gilgunnia project in the state’s copper-rich Cobar region.

“Essentially what we’re hoping is that perhaps we’ve got an analogy of the CSA mine and our rationale for that is when you look at what we know about Cobar-style deposits and compare it to Mallee Bull, it seems to be ticking most of the boxes,” he said. 

“The main features of those deposits are while they can be quite short in strike and modest in width, they’re usually long in the vertical plain and that’s what we’re seeing at Mallee Bull.”

Mineralisation at the project has extended as deep as 650-700m below surface. 

“The prize is that these deposits tend to yield a lot more over their time if you can keep the money up for exploration,” Tyson said.

Peel said Sandy Creek represented a “high priority” target but has so far maintained focus on ongoing work at Mallee Bull. 

Current efforts to fill in the gaps in Mallee Bull data include a continuing drill program, metallurgical testwork and follow-up investigation of a magnetic anomaly. 

“We’ve got about 10 high-priority targets identified to date and we’re looking forward to getting to those over the next six months,” Tyson said. 

“We had a couple of targets we identified earlier and one we drilled late last year, and we had some modest results there but we plan to be a long-term player in the Cobar district.” 

Shares in Peel were trading 1.2% down today at A40c.

Continental Coal and Village receive all approvals for finance agreement

Thermal coal producer Continental Coal says that South African based diversified mining company Village Main Reef (VMR) has received the South African Reserve Bank’s approval regarding the binding finance agreement between the companies, which was the only outstanding condition to its proposed strategic financing transaction with the company.

As previously announced Continental and VMR had entered into binding financing agreements, whereby VMR would subscribe for 100 million ordinary shares in Continental at an issue price of AU$0.08 per share, raising a total of AU$8.0m.

VMR would also establish and fund a mechanism for the sale of parcels of shares held by shareholders with a market value of less than AU$500 (being shareholdings less than a Minimum shareholding as provided for in the Company’s constitution) and acquire on a discretionary basis further Continental shares on market at a price of up to A$0.10 per share, thereby increasing VMR’s shareholding in the company to 19.9% of the issued share capital of the company.
With the final approval now received, Continental said it looks forward to completion and financial settlement of the placement next week and issuance of shares to VMR.

In addition, the company can advised that the closing date for the sale of small shareholdings has now passed and minority members who did not elect to retain their shareholdings will receive the sale consideration in accordance with the timetable and by way of cheque in Australian dollars to the address recorded in the share register as at the closing date.

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Fox soars on Pilbara sale

SHARES in Fox Resources have traded more than 18% higher today after the explorer announced a partial sale of its Mt Regal gold prospect in Western Australia for $A1.2 million.
Bruce Garlick
Pilbara quarry operators Hanson Construction Materials and Archipelago Nominees entered into the deal with Fox following on separate deals arranged in August last year.
“To date $400,000 has been received with the balance due once the mining leases are transferred to the respective parties,” Fox chief executive Bruce Garlick said.
“Fox will also receive a royalty payment for all material sold once operations commence.”
The company identified the project, 10k from Karratha, as being in an area with a number of existing quarry operations and containing a reliable source of suitable material to meet the construction boom already underway in the region.
A spokesman confirmed that the land sold had no mining value to Fox, but the company said it was nevertheless retaining its mineral rights throughout Mt Regal.
The parcels of land involved in the transactions are not expected to interfere with Fox’s exploration efforts at Mt Regal in terms of the search for gold and base metals.
Fox’s WA exploration program covers a number of prospective base metal and gold targets, and the Mt Oscar magnetite project, 25km south of the port at Cape Lambert.
Shares in Fox were trading 18.4% higher this morning at 4.5c.
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Supply side factors to continue impacting platinum price

The price of platinum this year would, in large part, continue to be determined by supply side factors, Thomson Reuters GFMS mining research director William Tankard said on Friday.
Discussing the firm’s latest yearly Platinum & Palladium Survey, he noted that further labour unrest was likely, as South Africa was moving into its wage negotiation period and shaft-restructuring plans were under discussion with government.
He told Mining Weekly Online that if labour disruptions persisted into the year, production in the local platinum mining sector would see a comparatively flat outcome in terms of output.
“Should these two factors [continued labour unrest and industry restructuring] be realised, we expect South African platinum output to fail to rebound this year, even after a calamitous 2012.”
He was referring to Anglo American Platinum’s (Amplats’) proposed restructuring, which, when announced in January, was aimed at removing about 300 000 oz from the market and result in the loss of some 14 000 jobs.
As part of the restructuring, Amplats would place its 1 and 2 shafts at both the Khuseleka and Khomanani mines on long-term care and maintenance, while its Rustenburg operations would be consolidated into three operating mines. In addition, the Union Mine North declines were likely to be closed, while the Union mine was to be sold.
Amplats was to disclose details of the outcome of negotiations regarding its restructuring next week, which Tankard said, was cautiously being awaited by the global market, which was seeking to determine how South African platinum producers reacted to market forces.
“Should restructuring take place and supply be kept off the table, we would expect reasonably positive investor sentiment to take on a small surplus and drive a pick-up in prices through the year, to average almost $1 600/oz. With more than seven months’ demand cover, or one year of South African mine production sitting as stock in the terminal markets, there is plenty of metal about,” Tankard said in an earlier statement.
“If we do not see an uptick in price, then the Amplats proceedings will not be the last,” he noted, adding that he was confident that the South African industry would face substantial labour pressure going forward, which would drive companies to undertake material restructuring.
“If this is realised, we will see comparatively flat production, which will flow through to positive investor sentiment that will have the potential to drive prices higher and dissolve into a modest surplus market,” he indicated.
On the demand side, the outlook remained delicate, particularly in Europe, which accounts for about 50% of global autocatalyst demand, but was showing a slow economic turnaround. He said this pointed to the need for platinum supply to be kept reined in for prices to strengthen and adequately compensate continued long-term investment in an industry with unrelenting cost inflation.
Tankard said Europe’s lagging economic recovery was likely to continue, which would lead to a muted performance over next year and potentially beyond that.
“Outside Europe, the outlook is cautiously positive [for] emerging markets, as well as developed markets such as Japan and North America. However, these markets are primarily gasoline markets where the metal used in autocatalysts is primarily palladium,” he added.
The survey revealed that, following seven consecutive years of gross surpluses, the platinum market swung to a marginal deficit of 83 000 oz or 2.6 t in 2012, seizing the growth of platinum stocks that have risen substantially since 2004.
The research firm attributed this, in most part, to supply side factors, with refined metal outturn from the three major sources, namely mining, autocatalyst recycling and the recycling of old jewellery scrap contracting during the year by 10%, 9% and 19%, respectively.
Overall, the withdrawal of platinum supply overwhelmingly originated from the mining industry, where the 10% drop translated to 620 000 oz or 19.1 t less metal, largely as a result of protracted episodes of illegal strike action in the South African industry, which drove a 12% drop in refined mine production.
“The overall quantum of the reduction was an about eight-million-ounce drop in supply during the year. In total, the mining industry contract by 600 000 oz of which about 560 000 oz was attributable to South Africa and, of that drop, a large amount can be attributed to labour unrest throughout the year, as well as the slow ramp-up on the back of that,” Tankard stated.
Meanwhile, the report revealed that platinum demand exhibited more stability, with an overall 1% lift year-on-year, with the stand-out performer being jewellery demand, which grew by 9%.
Overall, above-ground bullion stocks of platinum remained substantial last year, estimated at more than 4.3-million ounces or 134.5 t.
In terms of palladium, supply dropped by 4% during 2013, also owing to mining disruptions, coupled with a slight reduction in autocatalyst demand.
Nevertheless, palladium demand remained robust, increasing by 5%. The metal’s use in autocatalysts rose by 9% as a function of growing USvehicle sales. Overall, these outcomes led to a surge in the palladium market’s gross deficit, which expanded to over 1.12-million ounces last year, the largest market shortfall since 2001.
Tankard stated that the outlook for palladium remained highly constructive, with supply expected to remain constrained and demand expected to benefit from ongoing strength in the automotive sector.
Although the palladium deficit was expected to continue over the next year and beyond, it was anticipated to ease off from last year to below one-million ounces, while the price was anticipated to average around $725/oz.
The key outstanding bear factor for the metal would be investors’ attitude towards above-ground stocks, which, in spite of the almost perpetual deficits, were still large at around ten-million ounces.
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Regulator reports spill at Aurizon's Quebec mine

Shares of Aurizon Mines fell on Thursday after authorities in Quebec said a dam had broken at its Casa Berardi mine, spilling contaminated material into James Bay.

Some 150 000 m³ of liquid and 15 000 m³ of solid material was spilled, according to a release from Quebec's Ministry of Sustainable Development, Environment, Wildlife and Parks.

Shares of Aurizon were down 6.3% at $3.99 when the stock was halted pending news at about 11:00 ET. A spokesperson was not immediately available for comment.

Aurizon agreed in March to be taken over by US-based silver producer Hecla Mining Co in a friendly deal that values Aurizon at about C$796-million.

The company briefly suspended operations at Casa Berardi later that month after a contractor was killed in a vehicle accident.

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Dryblower and the power in the “oilman’s lament”

MOST mining people think there is little to learn from the oil world, though, as Dryblower has seen in past downturns, there is a lesson for tough times to be found in an old oil industry saying: “Please, Lord, let there be another boom and I promise to not piss it up against the wall this time.”

Who said that first is a mystery, and it might even have started as graffiti on a bathroom wall somewhere in Texas.

The genesis of the remark is irrelevant. It’s the sentiment and the power of the content which counts because the meaning behind the oilman’s lament is largely in line with what was said in this column a couple of weeks ago: we need a bust so we can get ready for the next boom – and hopefully not waste the wealth created in the way it has been wasted over the past few years.

What’s changed since Blower reminded his readers of the fact that we’re all working in a cyclical industry is the volume of the moaning coming from some of the new players in the game.

The unkind reaction to the bleating about the current market for small mining stocks being the worst in 20 years is “get over it”, because if you couldn’t see the downturn coming then you really are guilty of not paying attention to the tell-tale signs evident for the past two years.

Most of those signs were blowing off the commodity market and in the grim economic news from depressed regions such as Europe, where demand for minerals has plummeted as industrial production has slowed.

China too has not been immune from the global slowdown which was always going to follow the global financial crisis.

The point reached today, which is close to or actually at the bottom of cycle, feels a lot worse than it really is because this time around there are more people caught in the meltdown process, a result of the boom being one of the biggest ever – which means that the bust is one of the biggest ever.

Debating the size of the boom and the bust is pointless. What is useful is to consider the question in the oilman’s lament: how much of the pain in the downturn is a result of falling commodity prices and how is a result of failing management?

Commodity prices are undoubtedly a factor, but they are also an easy excuse for incompetent managers who failed to understand the most basic force at work in all resource industries – you have little, or no control, over the price received for your product.

All that a miner, or oilman, can do in controlling the performance of his business is to manage costs and hope that commodity prices are favourable.

Many of today’s managers in small exploration and mining companies have limited experience of cyclical downturns of the sort being experienced today.

They are boom-time babies who were quick to take credit for a rising share price which was due entirely to rising commodity prices, but unwilling to share the blame when commodity prices fall and they are left in charge of a business which has not taken good care of shareholders’ funds.

Two observations reinforced that point. One was a comment by Bill Beament, chief executive of the goldmining company Northern Star Resources, who was reported to have said over the weekend that the industry had itself to blame on the question of failing to control costs. “We should have been doing it 18 months ago.” Spot on Bill!

The other observation was from an investor who called Blower to comment on the fact that there was a stark contrast on display in the seating arrangements of delegates flying to the latest Mines and Money conference in Hong Kong – investors were in economy and managers were in business.

In a way that second observation is a variation of the famous question from the 1980s boom about “where are the client’s yachts” from a New York investment banker who was contemplating a day on Long Island Sound.

Cost control and ensuring that a company has sufficient funds to ride out a downturn are the two most important jobs of a mining company manager – plus an ability to pick talented staff and know where to explore, and for what commodity.

Commodity prices will take care of themselves, and while it is too early to tip an upturn it is possible to say that an upturn will come simply because there are billions of people in the emerging world who want a chance to live a first-world lifestyle and that means increasing (not decreasing) demand for minerals and metals.

But before we get to the tipping point where demand outstrips supply there needs to be a cull of the managers who took false credit for the boom and are now looking for someone else to blame.
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