PNG to lift lockdown despite surge in covid-19 cases

Papua New Guinea Prime Minister James Marape is pressing ahead with plans to lift lockdown measures in the Pacific nation this week, even as a recent sharp spike in coronavirus infections worries health officials.

Marape said a two-week lockdown in the capital of Port Moresby would be lifted from Wednesday, despite the country’s reported cases of covid-19 doubling over the past week.

“Whilst the spread is there, we have to adapt to living with covid-19 this year, instead of taking on drastic measures,” Marape told a news conference on Monday.

The outbreak is also hitting mining operations in the country, with one producer halting production after infections were detected among its workforce.

Mining generated $1.2 billion of PNG’s foreign exchange reserves from January to September last year, according to a World Bank report, which also cut the country’s growth outlook for the coming three years to 3%, down from 5.9% last year.

PNG had a total of 214 cases and three deaths as of Sunday, the World Health Organization (WHO) reported, up from 104 cases and one death the previous week.

More worryingly, WHO said it was likely the real infection numbers were much higher, given low rates of testing throughout the country.

“Testing in all provinces remains critically low, therefore ongoing transmission in other parts of the country is a possibility as population mobility continues,” it said. “Testing needs to increase substantially to understand the extent of transmission.”

Like many of its Pacific neighbours, Papua New Guinea appeared to escape the early clutches of the pandemic. But new cases in the past week were reported in nine provinces, including remote areas of the country, WHO said, adding the bulk of those had been traced back to Port Moresby.

The outbreak has also spread to Bougainville, where a 22-year-old man tested positive after flying in from the PNG capital.

Port Moresby was placed in a two-week lockdown on July 28, with only essential businesses to operate, schools closed, and transport services stopped.

Temporary hospitals are being set up in sporting faciilities to cope with a rise in cases, National Capital District Governor Powes Parkop told the Australian Broadcasting Corp.

“We simply don’t have capacity, that’s the bottom line,” he said. “We probably can create more space, but we don’t have enough medical officers.”

Mining industry

Concerns about the outbreak in the capital spreading more widely were underscored when Australia’s Newcrest Mining this week reported a covid-19 case at its Lihir gold mine.

Newcrest said the worker, a 30-year-old male, had flown in from Port Moresby at the end of July. It did not halt production and said it is continuing to test all arrivals three times during a mandatory 14 day quarantine period.

The OK Tedi copper and gold mine is midway through a two-week suspension of production, which the miner said is likely to reduce government revenue by $40 million, after last week reporting seven workers had tested positive for covid-19.

Exxon, whose PNG LNG project continues to operate normally, said it has already implemented enhanced cleaning procedures and modifying operating practices at all its sites around the world.

The coronavirus threat comes as Barrick remains offline amid a dispute with the PNG government.

What Are Jaw Plates?

Jaw plates are the most important wear parts for jaw crusher. It includes a piece fixed jaw plate and a piece movable jaw plate. Crushing ore by the squeezing action of jaw plates and stone material. Because of jaw plates need crush stone material, the material of jaw plates needs to withstand huge impact and grinding, so jaw plates need to use manganese steel to cast.

What Is Manganese Steel?

Manganese steel is made by alloying steel, containing 0.8 to 1.25% carbon, with 11 to 15% manganese. Mangalloy is unique non-magnetic steel with extreme anti-wear properties. The material is very resistant to abrasion and will achieve up to three times its surface hardness during conditions of impact, without any increase in brittleness which is usually associated with hardness. This allows manganese steel to retain its toughness.

Manganese Steel Chemical Composition

Most steels contain 0.15 to 0.8% manganese. High strength alloys often contain 1 to 1.8% manganese. At about 1.5% manganese content, the steel becomes brittle, and this trait increases until about 4 to 5% manganese content is reached. At this point, the steel will pulverize at the strike of a hammer. Further increase in the manganese content will increase both hardness and ductility. At around 10% manganese content the steel will remain in its austenite form at room temperature if cooled correctly. Both hardness and ductility reach their highest points around 12%, depending on other alloying agents. The primary of these alloying agents is carbon, because the addition of manganese to low-carbon steel has little effect, but increases dramatically with increasing carbon content. The original Hadfield steel contained about 1.0% carbon. Other alloying agents may include metals like nickel and chromium; added most often to austenitic steels as an austenite stabilizer; molybdenum and vanadium; used in non-austenitic steels as a ferrite stabilizer, or even non-metallic elements such as silicon. 

Manganese Steel Mechanical Behavior

Manganese steel has fair yield strength but very high tensile strength, typically anywhere between 350 and 900 megapascals (MPa), which rises rapidly as it work hardens. Unlike other forms of steel, when stretched to the breaking point, the material does not “neck down” (get smaller at the weakest point) and then tear apart. Instead, the metal necks and work-hardens, increasing the tensile strength to very high levels, sometimes as high as 2000 MPa. This causes the adjacent material to neck down, harden, and this continues until the entire piece is much longer and thinner. The typical elongation can be anywhere from 18 to 65%, depending on both the exact composition of the alloy and prior heat-treatments. Alloys with manganese contents ranging from 12 to 30% are able to resist the brittle effects of cold, sometimes to temperatures in the range of −196 °F (−127 °C). 

What Are Manganese Jaw Plates?

Based on crusher jaw plates working conditions, Qiming Machinery uses the following manganese steel grade to cast crusher jaw plates:

• Mn14Cr2
• Mn18Cr2
• Mn22Cr2

Mn14Cr2 Jaw Plates

This manganese steel jaw plate suit for crush soft raw material, such as limestone.

Mn18Cr2 Jaw Plates

This manganese steel grade steel jaw plate suit for crush hard stone, such as gravel stone.

Mn22Cr2 Jaw Plates

This manganese steel grader steel jaw plate suit for crush very very hard stone.

The Manganese Steel Chemical Composition

@Nick Sun  NICK@XZHUAGANG.COM