CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (36,199)	$ (37,084)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	15,510	17,969
Amortization of debt issuance costs and original issue discount	1,061	340
Provision for doubtful accounts	183	81
Deferred income taxes		4
Loss (gain) on disposal or impairment of assets	18	(59)
Loss on sale of Russian proppant business		350
Noncash lease expense	862
Stock compensation expense	1,586	2,254
PIK repayment on notes payable, related parties	(2,040)
Change in fair value of derivative instruments		(1,348)
Changes in operating assets and liabilities:
Trade accounts and other receivables	11,676	(3,777)
Inventories	5,830	836
Prepaid expenses and other current assets	(194)	(407)
Accounts payable	1,293	(1,341)
Accrued expenses	(7,938)	(4,303)
Income tax receivable, net	(9)	97
Other, net	(169)	2,126
Net cash used in operating activities	(8,530)	(24,262)
Investing activities
Capital expenditures	(1,085)	(1,179)
Net proceeds from asset sales	113	74
Net cash used in investing activities	(2,156)	(1,105)
Financing activities
Repayments on notes payable	(874)	(500)
Repayments on long-term debt	(14,533)
Repayments on notes payable, related parties	(25,000)
Proceeds from long-term debt	14,533
Payment of debt issuance costs	(218)
Purchase of common stock	(279)	(421)
Net cash (used in) provided by financing activities	(21,765)	1,928
Net decrease in cash and cash equivalents and restricted cash	(32,451)	(23,439)
Cash and cash equivalents and restricted cash at beginning of period	83,317	78,385
Cash and cash equivalents and restricted cash at end of period	50,866	54,946
Supplemental cash flow information
Interest paid	4,469	3,850
ATM Program
Financing activities
Proceeds from issuance of common stock under ATM program	4,606	$ 2,849
Pic Onyx Inc
Investing activities
Investment in PicOnyx	(684)
Issuance of Note from PicOnyx	$ (500)