Quarterly report pursuant to Section 13 or 15(d)

PROPERTY, PLANT AND EQUIPMENT (Details)

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PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Dec. 31, 2021
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment $ 305,595   $ 301,224
Less accumulated depreciation (119,566)   (115,703)
Total property, plant and equipment, net 186,029   185,521
Property, plant, and equipment, value of donated property 500    
Capitalized labor costs 100 $ 600  
Platinum catalyst metal      
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment 1,478   1,478
Catalyst      
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment 4,325   4,325
Land      
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment 5,400   5,428
Plant, pipeline and equipment      
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment 286,491   282,780
Construction in progress      
Property, Plant and Equipment [Line Items]      
Total property, plant and equipment $ 7,901   $ 7,213