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 7.  Property, Plant and Equipment 
 Property, plant and equipment consist of the following
 components: 
   
 
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 |  |  |  |  |  |  |  |  | Machinery |  |  | Construction |  |  |  |  |  
 | (Millions of US dollars) |  |  |  |  |  |  |  | and |  |  | in |  |  |  |  |  
 | Cost or valuation: |  | Land |  |  | Buildings |  |  | Equipment |  |  | Progress 1 |  |  | Total |  |  
 | 
 At 31 March 2014 |  | $ | 28.7 |  |  | $ | 212.5 |  |  | $ | 961.1 |  |  | $ | 115.4 |  |  | $ | 1,317.7 |  |  
 | 
 Additions 2 |  |  | 41.5 |  |  |  | 30.2 |  |  |  | 72.7 |  |  |  | 133.5 |  |  |  | 277.9 |  |  
 | 
 Disposals 3 |  |  | - |  |  |  | (1.7) |  |  |  | (6.6) |  |  |  | - |  |  |  | (8.3) |  |  
 | 
 Exchange differences |  |  | - |  |  |  | (1.2) |  |  |  | (52.6) |  |  |  | - |  |  |  | (53.8) |  |  
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 At 31 March 2015 |  | $ | 70.2 |  |  | $ | 239.8 |  |  | $ | 974.6 |  |  | $ | 248.9 |  |  | $ | 1,533.5 |  |  
 | 
 Additions 2 |  |  | - |  |  |  | 27.0 |  |  |  | 155.5 |  |  |  | (103.9) |  |  |  | 78.6 |  |  
 | 
 Disposals 4 |  |  | - |  |  |  | (0.7) |  |  |  | (65.8) |  |  |  | (1.5) |  |  |  | (68.0) |  |  
 | 
 Exchange differences |  |  | (0.1) |  |  |  | (0.1) |  |  |  | (1.9) |  |  |  | - |  |  |  | (2.1) |  |  
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 At 31 March 2016 |  | $ | 70.1 |  |  | $ | 266.0 |  |  | $ | 1,062.4 |  |  | $ | 143.5 |  |  | $ | 1,542.0 |  |  
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 | 
 Accumulated depreciation: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 At 31 March 2014 |  | $ | - |  |  | $ | (80.9) |  |  | $ | (534.0) |  |  | $ | - |  |  | $ | (614.9) |  |  
 | 
 Charge for the year |  |  | - |  |  |  | (9.3) |  |  |  | (60.9) |  |  |  | - |  |  |  | (70.2) |  |  
 | 
 Disposals 3 |  |  | - |  |  |  | 0.8 |  |  |  | 6.3 |  |  |  | - |  |  |  | 7.1 |  |  
 | 
 Exchange differences |  |  | - |  |  |  | 1.2 |  |  |  | 23.4 |  |  |  | - |  |  |  | 24.6 |  |  
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 At 31 March 2015 |  | $ | - |  |  | $ | (88.2) |  |  | $ | (565.2) |  |  | $ | - |  |  | $ | (653.4) |  |  
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 Charge for the year |  |  |  |  |  |  | (10.7) |  |  |  | (65.6) |  |  |  | - |  |  |  | (76.3) |  |  
 | 
 Disposals 4 |  |  | - |  |  |  | 0.5 |  |  |  | 51.1 |  |  |  | - |  |  |  | 51.6 |  |  
 | 
 Exchange differences |  |  | - |  |  |  | 0.2 |  |  |  | 2.9 |  |  |  | - |  |  |  | 3.1 |  |  
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 At 31 March 2016 |  | $ | - |  |  | $ | (98.2) |  |  | $ | (576.8) |  |  | $ | - |  |  | $ | (675.0) |  |  
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 Net book amount: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
 | 
 At 31 March 2015 |  | $ | 70.2 |  |  | $ | 151.6 |  |  | $ | 409.4 |  |  | $ | 248.9 |  |  | $ | 880.1 |  |  
 | 
 At 31 March 2016 |  | $ | 70.1 |  |  | $ | 167.8 |  |  | $ | 485.6 |  |  | $ | 143.5 |  |  | $ | 867.0 |  |  
   
   
 
 | 1 | Construction in progress is presented
 net of assets transferred into service. |  
   
 
 | 2 | Additions include US$3.2 million and
 US$1.7 million of capitalized interest for the years ended
 31 March 2016 and 2015, respectively. |  
   
 
 | 3 | This includes the accounting impact
 associated with the purchase of the Company’s previously
 leased facility at Rosehill. |  
   
 
 | 4 | The US$16.4 million net book value of
 disposals include US$10.9 million of usage of replacement parts and
 US$3.5 million of impairment charges on individual assets. The
 remaining net book value of disposals of US$2.0 million is related
 to the disposal of assets no longer in use, and do not represent a
 sale of assets. |  
 Depreciation expense for the years ended 31 March 2016, 2015
 and 2014 was US$76.3 million, US$70.2 million and US$61.3 million,
 respectively. 
 Included in property, plant and equipment are restricted assets of
 AICF with a net book value of US$1.2 million and US$1.3 million as
 of 31 March 2016 and 2015, respectively. 
 Impairment of Long-Lived Assets 
 The Company performs an asset impairment review on a quarterly
 basis in connection with its assessment of production capabilities
 and the Company’s ability to meet market demand. 
 During the years ended 31 March 2016, 2015 and 2014, the
 Company recorded US$3.5 million, US$3.7 million and nil of
 impairment charges related to individual assets which is included
 in Cost of goods sold on the consolidated statements of
 operations and comprehensive income. |